I think with bass they just don't have a lot of feeling in their lips because as you pointed out, they eat a lot of knarly stuff like crawdads, bluegill, etc. If a human popped a bluegill in their mouth, it would spine you like no other. For a bass, it's no thing. They don't want to feel that pain and so their mouth's have adapted so that they probably don't suffer a whole lot getting spined by a bluegill. I still absolutely think that fish feel pain. A fish hooked right through the nostril will flop around a whole lot more than one hooked in the lip. They feel it.