Prior experience and frame of reference. We've seen it happen before, and to expect it to not happen despite evidence to the contrary is foolhardy.
That's called progression. You use the "lesser" gear until you either got the tokens or was blessed by the RNG to get the "best" piece of gear. Right now you either get your law tome gear until you have enough for esoterics or get lucky with drops in Alexander. You get esoterics gear and use that until you get lucky with drops in Alexander Savage. It's not a stretch of logic like you're trying to present it.There is already a "best" and the other options are just illusions right? Why bother putting in three gear sets when only one or two pieces are any good?
To reiterate what I said earlier, you can have customization, but in the form of aesthetics. Merits that change spell visual effects or give you flavor abilities and things of that sort (because really, what BLM wouldn't want to be able to sprout Black Waltz wings and fly around areas with flight allowed?). Not something that'll change combat, but helps flesh out jobs and their place in-game. This way you get to stand out without leading to adverse effects to game balance.