Being pissed at the removal of theater is just dumb. It was not a great feature it was a mediocre feature that had issues and caused issues within the game. Plus no game ever keeps every feature from title to title all the time. As the game evolves some features that were once used or thought cool get dropped to make room for other features no matter if the players thought it was cool or awesome or not. The developers have the final say as to what is in the game or not and why, not the players ever.
Just becuse you cant make your aweseom montage of QSing or going for quad feeds is not really a reason to be upset unless you were one of the yt idiots that was trying to get famous on yt and then monetize the videos to make money off of it. Which really should be against yt policy since you dont own any of the footage in the game at all and would be using copyrighted material to begin with, which is not meant to be monetized.
If removing the theater improves the game play performance and smoothness then I am all for it and have no loss of feelings at all seing it gone.