Doesn't make any sense to me. Why try and manufacture an opener when we've got Michael Carberry making heaps of runs in County Cricket? Morgan's looked OK, but he's only made 1 score of any note in 5 Tests and 6 innings. Bell was in magnificent form before his injury, and should come straight back in. It's not like Morgan's been smashing Bangladesh and Pakistan around all summer. He's done a decent job, and has proven he's good enough for International cricket, but he's not done enough to mean the selectors should have to disrupt the positions of 2 batsmen just to fit him in.
Carberry in for Cook and Bell for Morgan makes so much more sense. Trott is not an opener, and Bell has an awful record at 3. Trott's been successful at 3, and Bell is clearly more comfortable down at 6, and has done more there in recent history than Morgan. Morgan has proven himself to be a good back-up batsman, but a top 7 of Strauss, Carberry, Trott, Pietersen, Collingwood, Bell and Prior looks much more solid than Strauss, Trott, Bell, Pietersen, Collingwood, Morgan and Prior AFAIC. That second line-up leads to doubts over 3 positions in the line-up, whereas with the first, only Carberry would be trying to prove himself.