Crafting does have quite a bit of use in the game:
-cosmetic stuff, from glamours to furniture, some of the housing items are very useful (mailbox, company chest, summoning bell, etc)
-sub-50 gear
-top tier raid content. When they raise the top ilvl, they add crafted gear for the previous top ilvl. Crafted gear with materia is much better than the old gear, and in many cases comparable to the new gear 20 ilvls higher. The new gear is gated behind tome caps and rng on drops/weekly lockout, so the brand new crafted gear is often the best gear available for the rabbits pushing the hardest content when it's first released.