Cesc has been tarnished by association. He grew up with us and then reached his productive years as the greedy bastards at the top of the club went on a vandalism spree. Now he represents the only chance we have of getting a quality midfielder given we won't pay the transfer fees and wages that other clubs accept. Everyone raves about Mata but Cesc is every bit as good, if not better. Mata probably wouldn't get in the Barca side either, he'd already be playing there if they wanted him.
It's not just about football at Barca anyway, lots of politics there and untouchable players, Now they are paying the price as an adaptable team like Bayern whips their arses. Cesc not being a huge hit at Barca is only partially a reflection on himself. If he wants to leave, and I don't recall seeing anything from the player that suggests it, of course we should be trying to bring him back. Makes sense financially and makes sense in terms of football. That's why we probably won't do it, because it would be good for the club as a whole rather than just good for the few who are raping the club.