If the airlines don't bond then we'll all end up paying up front. Most airlines you'll be able to talk to and come to some agreement if you decide to leave early as they'd perfer something rather than nothing and it'll always be cheaper than taking you to court.
As for paying for upgrades a lot of companies do it and some even reduce your salary for a period of time after the upgrade - so I find your comments Bad Robot very interesting. I agree that bonding or paying for an upgrade is not on.