Lately, I have noticed a lot of whining about various planes in AH. I am not refering to any real or percieved inaccuracy of various planes' FM. I am referring to when people whine about there being too many of a certain nation's plane or too little of another's.
What I am referring to is the whining about the numbers of US planes in the game. Now, getting away from any financial reasons (i.e. majority of players of AH are in US, thus better business choice for HTC to use AAF/USN planes) or real world reasons (i.e. much more comprehensive information readily available to HTC on American planes) for the decision, there are other reasons that should make since.
1) How many different airframes were
widely used (not refering to variants) by the US? If you go by America's Hundred Thousand, there were 11. Not counting the P-61 (sorry Rip), P-63, or F2A, that leaves 8 planes that were produced in a large quantity and saw widespread use. We have 5 of them, the P-38, P-51, P-47, F6F, and F4U.
The RAF had how many airframes that saw widespread use? 4 single engine planes (Spit, Hurri, Typh, and Temp) plus two twin engine planes (Beaufighter and Mossie). Soon, all 4 single engine planes will be in AH, and hopefully, at least, the Mossie will show its head soon.
Luftwaffe had 2 main single engine airframes (and countless variants of each), 2-3 twin engine fighters (don't know if you really want to include the 210 in that), plus the only jet that saw anything close to widespread use (I think we can all agree that the Meteor did not see close to the same level of use the 262 saw).
USSR had three basic airframes that were modified all over to produce several different versions (the MiG-3, Yak and Lavochkin's in all their many varied splendor), and I don't know how many, if any twin engine fighters they had.
Italy? Now this I am not sure about, so I won't even guess.
Japan had a ton of different fighters they used. They had the Zeke, Jack, Tony, Oscar, Geaorge, Frank, Tojo, Nick, Ki-100 (which I have never found a codename for), not to mention the floatplanes Rufe and Pete (which I think could be kind of cool in AH for a few sorties at least).
What I am getting at here is that US had a larger number of basic airframes than most of the countries, thus the large number of US fighters to choose from. I know this doesn't include all the different variants, but I am referring to basic airframes.
2) Why the large number of planes used by the Americans in WW2? Very simple, unlike the other countries, the US was fighting what boiled down to 2 very different wars, each requiring different types of planes. The ETO required the fighters to have better high alt performance and range (in some cases). The PTO was a carrier and island hopping war that required very different performance attributes. What I am getting at here is that I almost consider the AAF planes in Europe (though they were used in the PTO) to be from a different country than those of the USN.
The RAF fought mainly in Europe against the Luftwaffe, and the planes that the FAA used were often US built/designed carrier planes.
The LW fought a two front war in which the two fronts were very different. Hi-alt fights and intercepts in the west versus the low alt scraps on the east. That being said, on both fronts, the same planes were more or less used (whether it was right or wrong for them to do so, I leave to others to debate).
Italy had one basic front, the Med and Africa.
USSR had a single front (for the most part) and fought the fight they wanted (low alt).
Japan fought a single front war (more or less), but they were forced to build and design other fighter types due to several factors. In addition, as bad as the various forces in the other countries may have had a rivalry, in Japan, it was downright hatred (or so it seems) between the army and navy.
Ok, all that being said, lets compare the numbers of each country's fighters that are in the game now (prior to 1.08), including variants:
US: 5 airframes, 9 total
Brit: 3 airframes, 4 total
LW: 3 airframes (2 if you count the 152 as a 190 basically), 9 total
Italy: 2 total
USSR: more or less 2 airframes, 4 total
Japan: 3 total
Ok, what does this show? Not much

Seriously, this shows that the numbers are fairly correct based on history of the types used by each country, with the one exception being Japan.
Basically, what I am trying to say is that there is a historic reason for the large number of US planes being modelled. This is in addition to the rational reasons of business decisions and ease of researching a plane's performance.
-math