However, when I'm in "EXP + MF" gain mode, I'm forced to stay on MP1-3 so I can rush through the content as quickly as possible. Despite the MF, EXP and bonus drops gained from MP, it just doesn't make up for the clearing speed you have at low MP.
So I play at high MP anyway, from time to time, to have fun. But why should I have to be forced with the choice between efficient farming and having fun? Why can't the more fun option also be the more efficient?
High MP should yield at least as much as low MP, if not more. Right now, it yields far less. I'm okay with it yielding as much (not more), so then I could be happy playing at high MP, and those who prefer low MP could happily stick to that, and we'd both be just as well rewarded for doing what we each prefer. But if it's more rewarding than low MP, I think it gives people more motivation to want to strive for higher difficulty, and that's always something a game should have.
Here's one suggestion, but please feel free to help out with your own. Improve the bonus drops for high MP. For example, we have the MP1, MP5, and MP10 bonus drops as 1%, 36%, and 100% respectively. How about make them 1%, 75%, and 275% respectively.
Over 100% means multiple possible guaranteed drops. So if MP8 has 156% bonus drops, for example, then you get a guaranteed bonus drop with each drop, plus a 56% chance for another bonus drop.
EDIT: I think another novel approach would be to make the MF, GF, and EXP bonuses from MP multiplicative, rather than additive with our current bonuses.