Yeah, the large scale leves are pretty worthless. Anyone with any smarts wouldn't waste 10 leves on it. You could only (at best) complete 9 of them for basically a pittance in experience points which wouldn't even net you a single level on any combat job. Crafting leves are slightly better, but you're still better off crafting HQ regular leves and GC hand-ins for experience since there's fewer items required, and the XP per item is significantly higher.

I think they're just there to trick unwary players into wasting all their levequests.