Having PS4 take priority making PS3 users lose out is entirely to the benefit of Sony. It forces people to obtain a new console, driving sales, developers can spend more time on games for 1 console only, instead of having to develop for PS4 and PS3 (which is notoriously difficult to work on) and then more people are paying for PS+ in order to play with their friends.
It's not really that surprising that these issues have been so slow to rectify.
Really its the same as how apple users get an ios update for their old phone the same time a new phone comes out, and that 'amazing performance' they'll market at you is suddenly incredibly sluggish and painful to use.