You don't have to spend a single skill point to raise your crafting skill levels; however, if you want to craft level-appropriate gear, you'll most certainly want to spend a few points. You get the most XP towards leveling your crafting skills when deconstructing items not made by you (found items, quest rewards, stuff made by other players). Crafting items actually gives very little XP (we're not in Skyrim anymore, gone are days of making millions of daggers for XP and selling them for $...).

Personally, I don't find it "strange", just different. I, too, do wish crafting jewelry was an option; I believe I heard something about Zeni adding it in the future, but it's anyone's guess when/if that'll happen. Unlike Skyrim, you don't have to learn enchantments; you can craft glyphs to enchant your gear provided you have the right runes. Traits (which are distinct from enchantments) on armor and weapons must be researched before you can apply them to gear you create. I don't think it's unreasonable that items you research get destroyed in the process. As for "disenchanting" items, I don't even think that's possible; once you enchant something with a glyph, I don't believe there's a way to undo it.