Now, everybody has a choice to choose his own seat class. But with your proposal, passengers that are actually OK and would choice current seat sizes for a little discount would have to pay for everybody's else comfort.
> Now, everybody has a choice to choose his own seat class.
Not really. Right now if you need 5% more leg-space, you need to upgrade to business class, and pay 300% more for your ticket. That's not what I would call "a choice".