I know ^^ was just meaning to add to the list the aspect about craft/gathers needing to level also battle class to level themselves. Though now that I reread your original post, it seems you meant the "need" in a bit different context than I originally read it.
About comparison to repayng npc, something to note. A broken piece of gear is useless, it is the same as having an empty slot. If people for some reason were stuck k with broken gear with no crafter around they'd be stuck. Unmelded gear is not useless, it's just missing the icing from the top. There is never immediate need to meld it.