I see what you are trying there and I won't bait to the obvious "FFXI-hate" exemple
The main advantage of a customizable gear armory is to make them useful on the long road, it doesn't mean to have xx more different sets to gather but more likely having the possibility to be picky with your own decisions (gear wise), piece of gears that you can carry through your game playlife without discarding them every 3 months as a pure "glamour" or "desynthesize" gears trashs.
It would make the game more interesting by allowing the player to focus less on gears grind every new major patch and more on midcore / raiders contents that the game can offer to you... Trust me, it's very worthy, even more when you are able to see an unexpected 2 minutes and 30 secondes of FMV during an ending cutscene revealing to you the meaning of 2.0, the truth behind the crash of dalamud while answering many storyline questions, priceless moments.