Personally I feel people are being much too harsh on Ian Bell, Alistair Cook and Ravi Bopara. They may not be world-beaters but all three of them have potential to be good ODI batsmen.
Ravi Bopara averages over 40 for Essex in limited overs cricket, has a good strike rate and even an unbeaten double-century. Surely that means he is worth selecting to play ODI cricket? All 3 of his List A centuries have come at a run a ball, or better, and he's been doing all of this batting in the top order. So what do England do when they select him? Chuck him down at #7 and play him as an all-rounder, hoping he can succeed. During his limited time in international cricket we've seen that he does have the right temperament and can play some very good shots, now it's just a matter of the selectors have faith in him and giving him chances to bat in the top order. If they do this then I beleive Bopara can be a good ODI batsman, coupled with his bowling and fielding, England will have a good player.
Bell and Cook have both scored plenty of runs for Warwickshire and Essex at domestic level, have shone glimpses of their potential at ODI level and through their Test exploits we can establish that they are classy batsmen. Again, faith needs to be placed in them. After every series we hear a chorus of cries from English fans about who should be dropped, who needs to be picked and why their team aren't winning. I reckon a little bit more confidence for Bell and Cook, who are both confidence players, is all that is needed. Give them a decent run and then analyse their performances. Keep in mind that if you do drop them, players who have no experience at ODI level will probably replace them and they may not be successful straight away.