I like this concept, not just because of my high levels.
Different people like to do different things skill-wise and really unless you like digging and mining like I do, you're not gonna make all that much money. Especially if you're into combat skills, the cash rates on enemy mobs is very low and the stuff they drop isn't very valuable on auction.
I still think more options in /shop is still a good idea, but since that was vetoed this leveling up mcmmo skills thing could be a nice alternative.