Problem with doing 1941 Russian maps is that we only have the M43 uniform player models, which wouldn't fit. Making player models is one of the hardest things in BF2 modding and if we wanted to use the resources on it, it would probably be smarter to make winter models instead on another summer one.
edit:
And regarding the tank maps, as I said in the other thread: Tanks in FH2 are not the main focus, they are only part of the combined arms gameplay. If you had a map with only tanks, several of their features would be completely useless, like: tank passengers, high explosive shells, coaxial machineguns, armored skirts etc. It would mostly be point and click. So without infantry and pak, the tank experience would be very limited.
And because of how powerful they are, tanks will always be in the minority compared to infantry, so you won't always get one. But then again, infantry players also don't always get a scoped rifle: their limited nature is what makes them cool, otherwise they would just be spammed.