Crafting is effectively its own sort of thing, combined with gathering. For the most part, normal play and endgame tome collection will get you plenty geared out and crafting won't really matter. Your very first character through might benefit from picking up some crafted gear from the AH or even just vendor "white" gear if you happen to feel you are lagging hard in the 30-50 stuff, but as for being able to make gear yourself while leveling the first time through that is actually near your level? It tapers off hard after 15 when interdependence between different types of crafting and gathering really start to come to the forefront.
Crafting is heavily intertwined with -all- the crafting disciplines, and leveling any single one is difficult (until Echatl and Moogle quests; later on that) and to make anything worthwhile you'll need lots of crafted mats from multiple disciplines, except Culinarian kind of does its own thing for the most part.
In the 40s you'll unlock beast tribes, and the Ehcatl beast tribe is for crafters/gatherers. You can complete the quests with only having the three gatherers at like level 10 or something, and whatever crafter you want. But it is still a very time consuming process and to use the levels you gain, you'll still need materials that are made from other classes. In the 50s you'll unlock the moogle quests in HW, which is the same sort of thing, but only for crafting. Again, easy to level, but you will still need the mats.
Long story short; you don't need to level any crafting thing and none really -benefit- one class over another minus a small decrease in repair costs from Armorsmith/Blacksmith/Goldsmith for paladins. The problem is, you'll need to level those to keep pace with your normal leveling, and that becomes a major pain if you aren't doing both types of gathering and crafting. Or just buying gil from a goldseller. Do crafting/gathering if you like the playstyle after you try it; don't do it to supplement any specific class.