Having recently returned to microarmor from 15mm gaming I might be able to shed some light here. Especially since my return to microarmor was encouraged by a friend (Mark Luther) who really, really dislikes larger 15/20mm figures and 5:1 games but also prefers more detailed games (which I don't like as much).
1. Figure Size vs Unit and Ground Scale
For 15mm/20mm gamers this is generally not an issue. We larger scale gamers often play games in which a stand represents an entire platoon and 1" is 40-50 yards. But we do this while refering to the models as individual tanks and figures as individual figures as if we're playing 1:1! Our villages are often treated in the same way so that a two buildings on either side of the road are an entire French "town" but we then fire several hundred scale yards THROUGH the village (down the road) at an enemy tank. From a visual 1:1 toy soldier perspective it makes perfect sense. From a strict scale perspective it's absolutely, 100% silly.
In Flames of War (have played it since it was first available in the US, but not as much lately) it's even worse in that mere companies receive support assets more appropriate for an entire division and arty ranges are scoped so that arty appears on the table with the infanty company! (so they can sell more figures...off-board arty need not be purchased.)
We microarmor gamers like to think of our games as being more accurate with respect to scale issues, even when vehicle models represent a platoon or an infantry stand an entire squad. But if the models represent a platoon or squad we're still dealing with the same distortion as 15/20mm gamers but it's a little less noticable.
On the other hand even 1:1 microarmor gamers are subject to delusions of grandeur. A friend is a die hard 1:1 gamer who scoffs at 5:1 games but then puts on scenarios he decribes as (for example) "representative of the attempted breakout by the Warsaw mechanised Brig and 1st Light Tank Bttn against the 4th Leichte Div on Sept 18, 1939 near the town of Tomaszow Lubelski in southern Poland". So, a couple of 1:1 tank platoons are thought of as an entire brigade or battalion which is simply the reverse of platoon-scale gamers thinking of tank platoon models as individual 1:1 tanks.
The problem is that 1:1 gamers (like my friend, those who play FOW, and myself before I went back to platoon scale) want the tactical flavor/detail of 1:1 gaming but also want the sweep, scope, and combined arms aspects of higher level gaming. And we "5:1" gamers want the sweep, scope, and combined arms aspects of higher level gaming but also want the rich tactical flavor of 1:1 gaming (too much abstraction and the game becomes dry and lifeless.)
We ALL want to be Patton hunting tanks with a bazooka. We just arrive at the same destination from different points of departure.
2. Accuracy Snobbery
I hate to say it but for many of us in the 15/20mm community we see microarmor gamers as accuracy snobs tilting at windmills (remember, I'm writing this as a recent convert back to microarmor.) Microarmor gamers seem to be more interested in getting things "accurate" such as visual scale and technical accuracy with respect to hardware than having fun. Larger scale gamers seem more concerned about "fun games with toy soldiers".
The micro/accuracy group scoffs at the visual inaccuracies of a huge 20mm tank representing a platoon and firing hundreds of scale yards across down a twisting boccage flanked road which would be truly impossible. But it seems that many micro/accuracy gamers will endure painfully detailed rules which result in lots of people standing around filling out paper forms (doing tax returns is more fun) or flipping through page after page of data (as if the data isn't classified and there's enough real-world data to model from).
The result is that the 15/20mm guys are completely bewildered as to why someone would want to stand around filling out forms and consulting massive charts of questionable accuracy in the pursuit of "accuracy" when the player experience is one of, well, sitting around and filling out forms, looking up lots of data, and doing lots of math. And after doing this for several hours and getting only a few turns done everyone says, "Gosh, that was realistic." So are root ** CENSORED **.
3. Fun Snobbery
At the other end of the scale those of us with an interest in accuracy (that's me when it comes to tactical decision making) are often bewildered by the "fun snobs" and system fan boys. I finally gave up on Flames of War when it became more of cult and less of a game. Here's how bad it is: FOW guys have posted on forums that "overwatch" is not a real-world tactic! That's right, according to them the core tactic of modern warfare was made up by grognard wargamers who dislike FOW.
FOW fan boys often say that since wargaming does not involve acutal shooting, killing, and suffering all wargames are equally unrealistic and, therefore, FOW is just as accurate as any other wargame (the others are simply unplayable). One even said on TMP that since the Germans lost the war all miniature wargames should result in German losses to be accurate, and since that doesn't happen all wargames are equally inaccurate. There's simply no reasoning with such whackiness.
The fan snobs are also VERY hostile if one points out that FOW is a marketing tool to sell products and not a game representative of modern tactics. After spending many hours supporting local FOW tournies and getting local shops to carry FOW products I finally got fed up with the fan boy attacks. Here's the usual sequence:
FOW fan boy: FOW is so historically accurate and fun at the same time! Don't you agree?
FOW gamer/tourney organzier/store recruiter: Well, it can be fun and the core system is very simple and clean, but it's game tactics are really the opposite of historical tactics to encourage aggressive tourney play. And the codex creep is slowing the system down with all of the special rules.
FOW fan boy: You FOW hater, hater, hater!
A couple of guys who played on my terrain at a FOW tourney even called me a FOW hater for pointing out that the Festung Europa book didn't live up to the BF marketing hype...and that was AFTER they played in the tourney I supported with 5 tables of terrain.
4. The Business
As to microarmor availability, it's not just microarmor. Even FOW has its problems. Here in Atlanta three different shops which carried FOW went out of business. They didn't go out of business because of FOW but FOW didn't help them survive either (I bought lots of their stock at very deep discount, often at wholesale cost).
Historical gaming is a very small niche market, WWII gaming is a big segment of that niche, and 15mm/20mm gaming is the more popular segment of the WWII segment compared to microarmor. At some point the market segment becomes so small that a B&M store cannot generate enough churn to justify dedicating valuable shelf space to a product whether it's FOW or microarmor. A retail shop pays for every square foot of retail space in rent, utilities, and staff. The products that generate the best return per square foot win and I don't know of any pure B&M store which thrives on historical gaming (but I can think of many that have gone out of business...) Even pure B&M train shops are having a hard time competing with the internet and larger multi-hobby stores such as Hobbytown (one fellow who owned and closed a local train shop told of people who came to his shop to examine products and then bought online from interent discounters with lower overhead).
5. MOST IMPORTANT THING
So, I suppose each community is a little "hostile" to the others because each has it's own perception of how games should work. Some are 100% dedicated to a particular rule system and can't abide any critique. All want high level combined arms with tactical detail and flavor. Each focuses on particular aspects of gaming and is usually unwilling or unable to recognize flaws in its reasoning (eg 5:1 gamers usually don't realize they're playing a 1:1 game and 1:1 gamers usually overload their games with too many figures or they describe their games as larger scale engagements.)
But the most biggest problem with microarmor is, as my wife says, "They're too darn small to see!"
Tim
PS Last night I played in a friend's 20mm WWII game and I decided that Mark "My Accuracy Snob Friend " is right. The bigger scales look silly to me after playing a lot of microarmor recently, so I've made the final decision to switch my 15mm WWII collection to the "too small" microarmor figures. But I still don't like painfully detailed rules and will stick with my fun hand-full-of-dice approach.
PPS Things are changing too. I've read about AK-47 gamers using microarmor. AK-47 is a beer-and-pretzel game about bush wars in Africa. Very colorful stuff and very interesting that a community of gamers would switch from 15mm figures, which should have more "character" than microarmor, are willing to go 6mm.
One very important reason: you can get anything you want in 6mm for moderns!!!! So GHQ, get working on my request for more Third World militia figures from the middle east and Africa!!!