For the folks asking for signatures to be added to gathered items and dungeon drops... that's kinda ridiculous, and I feel a bit of a slippery slope argument in a way.

The difference between crafted items and gathered items is that gathered items are typically expected to be used up. Whether you NPC it, turn it in for seals, eat it, or use it in a synth, gathered items are expected to be used up, not shown off. Hell, unless you put it in your bazaar, nobody could even see the name on them anyway.

The difference between crafted items and dungeon drops is that the dungeon drops people actually care about are U/U anyway for the most part, save a few items here and there. Getting your darklight pieces signed is a tad redundant. Being able to say "Yeah, I actually farmed this Chiran Zabran's Tempest instead of buying it" might be nice, but making a system to do that might be more complicated than it may be worth.

In addition, a lot of these arguments seem to be assuming that all three types of classes are equal, and they really aren't. Battle classes are inherently important to the game, they're how you do all the quests and other fun stuff, so it's not like incentive is needed there.

Gathering classes have an inherent incentive in the form of loot: Playing it is basically pure profit no matter what you do, and unlike battle classes you actually get some say as far as what loot you get.

Crafting classes... let's face it, while they do have methods of making money at the moment, it's very subject to the whims of the market. When selling loot or materia, it may suck when someone undercuts you and you have to sell for less than usual, but crafting has that initial investment that means you may very well wind up selling the item for less than it cost you to make it, especially when you're leveling and have to worry about xp instead of making whatever's in at the moment. The other class types, you can hop on and usually come out ahead across the board, unless you spent an entire night wiping to fights. Crafting can have you log on, actually finish all your synths, and still come out worse than you started, and that's painful. Leveling a craft is not a necessary part of the game, and really there's not a whole lot of incentive to do so. Signatures are a simple vanity addition, but they do add a few incentives to crafting. Pride in wearing a set of gear you made yourself. Entrepeneurship, in trying to build a name for yourself and charging a markup for name-brand equipment. Just simple amusement. At the very least, adding this feature to crafting sure doesn't hurt anyone.