It's probably worth mentioning that the reason that it's breaking down is your preference for riding without gloves. When your bare sweaty hands are tugging away at the rubber hoods, it's much harder on the rubber than if you were doing the same with gloves on. My advice is that if you have to replace the hoods afterall, find some cool/comfortable cycling gloves that you won't mind wearing and try to make it a habit. If you insist on not wearing gloves, expect the condition to repeat itself in due time.

-Jeremy