I just noticed that a few people took issue with my remark about trunk bags and panniers not fitting into the "Wow! That's functional!" category.

I guess I chose the wrong expression. Yes, of course my trunk bag/pannier set is very functional. I use it to carry everything I need for work, for overnight stays, and for emergency repairs. But it's still just a bag that gets strapped to a bike, and it even requires extra hardware just to mount it.

A frame bag, on the other hand, takes advantage of a wide open gap that's just SCREAMING to be converted to storage space. I think making use of this existing space is a lot more clever than adding extra gizmos (like trunk bags and panniers) to other parts of the bike. "Functional" may have been the wrong word.