The guns for the most part used by the Japanese on their tanks were pretty crappy. I think the most successful main gun they used was the 47mm and that wasn't very effective. The problem with the Japanese when they made their tanks is that they did not expect a general war with anyone but rather limited engagements like they were undergoing with China and border clashes with the Soviets. As such, they felt that they weren't likely to face anything larger than a light tank and didn't need to make anything larger or larger guns. They felt that the 47mm was more than enough because it was easily able to penetrate their tanks and as such, used their light tanks as the benchmark for how effective the guns should be.
Successes during the invasion of Malaya and the Philippines further reinforced the Japanese belief in their doctrine that they didn't need anything larger. In addition, priorities also shifted towards aircraft and warship production which limited the amount of steel that could be used to build larger tanks. That's why most of the larger tanks were only produced as prototypes or in very small numbers.
ack-ack
The 37mm guns (Type 1 and Type 94) were not as capable as the 37mm M6 mounted on our M8, so saying they have the same armament is incorrect.
Well said, Ack-Ack, but even though the Japanese tanks/tankettes were inferior, they still saw action and may be up for recognition in the game. Although not as effective as other tanks from the war, they would stand to add to the diversity of play.
As for the second quote, I never said their arament was exactly the same, they were similar at best and nowhere did I say the Japanese 37mm and the American 37mm were congruent, you said that yourself. Tankettes from Japan could go roughly 30 mph (rounded as a conversion from 45 km/h). Who is to say the Japanese tanks need that much armor? The M3 and Sd.Kfz 251 can be pierced by multiple AP rounds before blowing up, and HE rounds are more effective. Think about other planes in the game, is the I-16 a game-changer? How about the M-16 or the aforementioned Sd.Kfz 251? These craft and vehicles add a diversity to the game that would be very limited had there been no switch from the big-names from the war. That's just my $.02 of a retort.