Exactly what Luvnest said. They allow you to be more mobile and not have to stop to get that deadly DPS. Heck, I have had Soviet opponents run at me with a shock squad and then realise just how deadly G43s are!
Again, a fine point being made here. Interrogation is great, especially vs USF. You've just have a big battle, the forces have retreated and interrogation could provide intel about where his forward retreat point is, drop a flame bomb on him from your mortar HT and GG. And even if that kind of thing doesn't happen, it can provide you with a vital look into his FOW. Just knowing that point XYZ is undefended is worthwhile enough IMO.
Just a note: G43 and Mortar HT aren't in the same commander.