The " You can always do a deal" argument doesn't stand up. If prize structures were flatter, players could always do a deal to make them steeper again, but I don't think that would happen too often.
Woot?
"i tell you what guys lets do a deal, top prize is £1500 but i'll take £2000.........ok?"
Erm, i think not.
As for the dealing argument not standing up, i think you'll find in practise it already is.
The fact is there is no real lobby for flatter structures, so few actually make it the effort to change things and the folks that shout loudest are those opposed to change (not necessarily because they disagree with the change itself).
Look at this poll, 1% of members voted...........................