Most of the devs I know have a habit: They must do something every day 
Payment protocol stuff was a business demanded feature, intended to address some of the problems that have cropped up with Bitcoin URLs. Its certainly not something sexy or exciting to work on.IMO, bitcoin is mainly a monetary system with secure transaction function. As a monetary system designer, business oriented practice is a too low level of concern. FED will never care about what paypal or VISA is doing, that is many levels lower down the importance chain
The monetary policy of bitcoin has already been written into stone by Satoshi, but there are still many area to improve regarding the performance and reliability. Only the security part will bring a normal user lots of headache. I just heard that someone lost 150 coins in an offline wallet with a 20 character strong password and he doesn't understand at all what went wrong
