I can't imagine that you'll be forced to choose "just one" and yet I see the problems both with allowing the hardcore to max all crafts, as well as the problem of forcing them to simply level them on a separate mule. However, if those are the only options that you're looking at, you're looking at a false dichotomy.
I could see them putting limits on the number of items that you can craft "perfectly", which would allow for a lot of niche marketing opportunities, and while that could tremendously promote people making mule after mule, I think at some point it would force players to either accept the idea of having just one character for crafting, or being one of the few hardcore crafters to level multiples (but will never be able to craft everything optimally regardless).
I haven't put much thought into how I'd like it to be, but on an unrelated thought, I was thinking it would be cool if you could attract monsters by cooking. Probably something that will be a leave-related feature though, rather than a gameplay feature.
Ok, now we're going to get slash fiction of Wint x Kachi somehere... rule 34 and all...
Never confuse your inference as the listener for an implication of the speaker.
Good games are subjective like good food is subjective. You're not going to seriously tell me that there's not a psychological basis for why pizza is great and lutefisk is revolting. The thing about subjectivity is that, as subjects go, humans actually have a great deal in common.