I've made no secret of my opinion that GP2 has been weak lately. McLaren, Red Bull and Ferrari put their development drivers in FR3.5 and I expect more teams to follow suit.
GP2 seems to be in a bit of a self perpetuating spiral. Once drivers who won in GP2 stopped automaticaly progressing to F1, anyone being groomed for an F1 seat is being placed elsewhere (i.e. FR 3.5, like you said). This in turn means less F1 apprentices in GP2, which means even less progress to F1, and so on and so forth.
The problem is, it doesn't really matter if you win in GP2, don't win in GP2, or win in any other feeder series. If you don't have a big fat cheque your unlikely to get into F1 anyway.
The way GP2 should work is to produce drivers like Rosberg and Hamilton, who got into GP2 on merit, won, and progressed into F1. Filling the field with pay drivers or people who have just hung about for 4 years doesn't highlight the talent on the F1 stage like it should. I'm not saying all GP2 drivers are pants, but its definitely not the 26 best 2nd tier drivers in the world battling out for an F1 seat its sold as.