100% agree, it shouldn't be better than the mp40 or thompson, different but similar, as it is now. But for that reason it should be unlocked alongside the ppsh as a 2nd different option for the same price as the MP40. Its grind is currently 1.5x longer and assuming you don't buy the Ppsh it costs 67k more when you get there. If you factor the price of the ppsh to ease the grind then you're paying 225k more than it's Ge/US equivalent, bit harsh for a like for like weapon for new players, I think.
In my opinion the smg situation and grind is a huge problem in SU recruitment. SMG's should be the bread and butter weapon and SU new players just don't want that hassle if it's easier on another faction to get the competitive SMG.