So suddenly from all the realism, design, doctrinal style etc.. reasons it comes down to the only argument that they just don't appeal to you.
No, the reasoning is that their ground forces did not have the strength to go toe-to-toe with the Soviet Union or the United States. They were a Naval power and an Air power, but they did not do armoured warfare well. In CoH2 they could have an early-game, and a weakened mid-game, but they would have zero late-game. How would they face off against E8's, 85mm's, let alone IS-2's?