How about this? Make us to choose weapons in the game

Whatever the weapons you have, you can only choose the weapon that you really can use in that campaign.
If you unlocked the stg , than you can choose it in normandy and berlin, and you cannot use it in moscow.

Thats a great idea! Moscow particularly is one of those campaigns that has rather massive disparity in equipment and quite obviously people dont play it = bot games.

So when ever matchmake throws me in moscow, I just have to quit untill I get to use weapons I like.
Sounds super fun & convenient.
Or even better, I never get moscow maps with my setup and moscow maps remain unpopulated & unbalanced bot games.