If he'd had a great 12 months and this deal happened next January (with the loan back of course, so we'd have him for another 18 months) I don't think anyone would begrudge him the move and we'd all feel as if things were done the right way
To be honest I don't think many would have begrudged him if he'd gone to Liverpool, Spurs or even somewhere like Southampton and it looked like we'd done at least OK out of the deal.
Its more that he's gone, with the greatest respect, to a club like Norwich in a deal which seemed to get rushed through at the last minute.
Even the Norwich press were last night reporting they'd left it very late to make an approach. When you leave it that late it would have been easy for us to stick it out to the deadline and say come back in the summer. I can't imagine you'd get any less for him then.
Assuming what TM has said is true and Maddison didn't ask for the move it wouldn't have caused any issues to keep him here until the summer.
Add in the fact that we appear, from the vast majority of reports, to have sold him 'on the cheap' and its not hard to see why the reaction has been so negative.
We've sold him to a team we could be in the same division as next year at a price clubs like Gillingham were rejecting!