I can't understand how running something like a 30t "big ring" with a 24t bailout that requires you to stop, get off the bike, manually shift back and forth during a ride is a better compromise than simply learning to set up and maintain a front derailleur and keeping a true wide-range of gearing. It seems to me that at this point you've got a big ring that still severely limits your top speed with the hassle of stopping and manually switching to a granny for longer climbs, worst of both worlds if you ask me but I must be missing something, so please enlighten me.
You'll have to pry my 38t big ring out of my cold dead hands..more gearing = more fun on the bike IMO.
It's done to have a more reasonable handlebar setup (reverb button in the right place), reduce the constant noise from the front derailleur on rough trails, and shave some weight.