Sort of. To an extent the issue is one of engine power: the Japanese were trying to make leading-edge fighter aircraft with powerplants that (in 1941) were putting out around 950-1100hp. This made them economical and thus long-ranged, but especially to maintain the range the Japanese sought for Pacific operations weight had to be pared right down.

In Europe, this was less of an issue. Although the Bf109 and Merlin-powered aircraft started out with around 1100hp (a few years earlier than the Japanese), it was always appreciated that more power would become available and in Europe much shorter ranges were acceptable. The future need for long-range bomber escort was little appreciated.

America had the advantage of having a fairly heathy aero engine industry, and manufacturers could design aircraft around engines producing fairly good power (albeit not at altitude, but this was not realised to be important at first).

Furthermore, being able to tool up with the lessons of early European combat in mind, manufacturers like Pratt and Whitney and Wright leapt ahead in pushing the design and mass production of engines in the 2000hp class- and they had the science and metallurgy to make these are reality. This gave a good margin for 'luxuries' as the added weight was less of a relative burden on an already-heavy aircraft.

For Germany, the Fw190 was also built around a 2000hp radial and was very well-armoured, and this in 1941. One could say that the Fw190, Thunderbolt and Typhoon were all similar in this way, with an abundance of power allowing a generous armour fitment.

Soviet aircraft had pilot armour and made use of armoured glass and fire-suppressed fuel tanks using engine exhaust to displace air around the tanks. They tended to be very short-range (operating from front-line airfields) and deliberately small. The aim was to extract maximum performance from aircraft that generally ran on less power (the Yak 3 had very high performance on 1200hp, albeit with short range and lightish armament).