The series was ultimately decided by the one match where Australia did not bat out their overs. The English batsmen were not put under pressure in the first two games, but once they were, wicket taking became a lot more vital.
But I agree, wholesale changes are not warranted. Kieswetter warrants more chances; it's not like the next guy up is going to come in with the experience of having faced 100 mph. You want to see what Kieswetter does with that, though admittedly, Bangladesh probably won't yield conclusive results for that test.
The top order could use Trott's determination. In contrast to Pietersen, this provides someone who will let a long innings be its own form of dominance, rather than having to force the issue.
I would aim to bump Pietersen back to 4, so I would try Bell at 4 while he is injured. Looking at Mike Hussey, Eoin Morgan shouldn't suffer from batting at 6, so I see no problems with the order.
Both Bresnan and Wright are so confusing. Bresnan is apparently more a bowler than a batsman, yet he seems much more natural with the bat, especially against Australia. Likewise Wright is meant to be the batsman, but after years around the England team, he still seems to have way too many flaws. I would actually go as far to say he was more awkward than anyone above or below him.
I'd be inclined to suggest playing Yardy or Bresnan based on what the pitch offers, but Bresnan got pitches that offered something and he didn't use them. Yardy was definitely the best "bits'n'pieces" player, but it feels like a win by default.
I don't know anything about Shehzad or Finn in one dayers, but I'd wager they do offer something with the new ball.
It sounds like a lot, but only two real changes are glaring. Drop an all-rounder for a top order batsman and drop an all-rounder for an opening bowler. Simple, really.