Don't understand making weapons when quests give them?

[Zyeriis]

That didnt answer his question.
There is no point in leveling a craft to 50 as is, as there are much easier alternatives. Also endgame gear that can be crafted is not only limited but a disappointment.

Some one needs to make the base weapons for relic weapons. You know those green weapons that you have to attach 2 tier 3 materia to. Also, quests run out eventually, which means free gear runs out, especially for second (and third, etc.) jobs to level up in. There also needs to be a source for making weapons to convert into materia after spiritbonding. Which is where the other crafts come into play. Then there's alchemist and culinarian (though not enough people actually use potions and food since it's hardly necessary).

I'm not denying that are problems (there's tons of them) but I wouldn't go as far as saying that crafting is completely useless.