Saw it mentioned in passing in another thread and I think its a good idea. For the next 20% bonus reward, a completely new chest would be interesting. I know there are a bunch of skills mentioned in the AH (Grants Buff Section) that haven't even been introduced yet. Maybe a choice of a couple chests that include a few of those buffs?
as for the point of the thread its to get the idea out there and create an open thread for suggestions on new chests.