Hmm, there's at least 3 quests I know of that require raw ores, and more if you count those quests which require you to get ores and melt them into stuff. None of them really give much PP though.
As for mining giving more PP/EXP... I think mining should be the one thing that doesn't give you more skills. It's purpose is to make money, or get you the means to craft items. In other words, the means to get experience. Unlike fighting or crafting, there's nothing that can really be learned from hacking at a rock and collecting what falls out. A 5-year-old could do it...