I actually dislike this idea of having a leves refill... If you can unlimitedly increase leves, that means as long as you have the gil, you can keep buying the items from MB, and then turn in at the levemete. This means as long as you have the gil, you can clear the MB for every single leves item (regardless of leves levels), and throw everything at the levemete without much thoughts. And you can do this for all your classes... which means as long as you're loaded with gil, you can level all classes to level 70 within a day or two. It doesn't sound like a fun game to me, and it promotes gil-selling activities.

I think grinding is a process that has to be there, whether it's DoH or DoL or battle classes. If you remove this component, the game will break.

Sorry, but I don't quite understand what you mean by the 30min - 24hour timers restriction. What are you referring to?

Crafting 'dungeons' could be interesting. It's just something that very hard to implement.