Dunno about you, but I've gotten money, experience, and really pretty gloves from RP (the one RP I really got into, and enjoyed). Not like I wear the gloves, ever, because they're like, fancy gloves, but I keep them in my pack and look lovingly at them from time to time.
I do agree that I like fighting the monsters, not necessarily for the fighting aspect (but yes, it is fun to rampage about the rats for a bit), but for the leveling ones (rampaging the Trepors instead). It's easier to get PPs from fighting monsters than mining, or metallurgy. That's the only thing I really miss when the monsters get impervious; that buying the next level in Metallurgy costs several hundred PPs and I'm running out of ways of getting lots of PPs.
Doing quests is a nice way to pass the time. Then if not mining, then metallurgy. If not that, then pop into a tavern or other populated area and try to get involved with something. Doesn't always work, and sometimes bad things happen, but that's life, eh?