Its not pointless. There ARE users who had been requesting this as far back as 2009 in the Eorzeapedia Suggestion box back before the game even released.

There are players who WOULD use this.
And as far as I can tell, If SE did it, they would be the first MMO to do so. (if not any video game period allowing players to actively choose which hand they use.)

Why anyone would argue against a positive Character customization option that would increase a bit of the uniqueness for some characters is beyond me.

Its like people yell and scream "We want more customization!" before the game releases, but then when someone asks for it all you get is "ehhhhhhhhh"