This is one of those ideas that sounds good when you apply it to everyone else.
Personally I want to own my shares immediately. You never know what's going to happen and what technicalities will let VCs/the board/others fire you before you're vested.
I still wouldn't trust the small print not to taketh away. Typically it involves something like accelerated vesting as long as you're not fired "for cause"; but who's to say what kind of charges might be trumped up to get around it? In which case, you'd want a clause covering departure for any reason -- but then you might as well be vested from the start anyway.
Personally I want to own my shares immediately. You never know what's going to happen and what technicalities will let VCs/the board/others fire you before you're vested.