i'm not saying they should spend all their enegry on develpoing a better PIP, but in the next update they could start from that, for example: in the RHS mod ACOG scopes when switched to PIP, the scope becomes drastically darker, (doing the opposite of what an ACOG scope should do) if they just made it better, maybe adding more options such as brightness and what not it would add that something many games dont have, although we have seen perfectly working PIP scopes on insurgency, which is on the source engine.
I have no idea how PIP works, but i am sure they can do something to make it look and work better, who knows.... maybe even making it stress on the GPU instead of the CPU.