WoW already has a system of sorts like this for the hybrid classes (i.e. classes that have specializations for more than one role), and as some who mained druid (tank/healer/dps) and demon hunter (tank/dps), I can safely tell you literally all it does is auto-sort you into whatever queue you checked is more lacking (on WoW, it’s always tank priority because pretty much no one wants to tank, then healer) so it’s not going to be any different from how it is here aside from the fact you can change your classes on FFXIV.

Letting you pick realistically just isn’t going to happen either because most of the time, healer queue is instant queue due to the large shortage of healers. Tanking typically is a few minutes more. DPS always is 15 minutes minimum (unless you’re doing Crystal Tower, and even then it’s longer than tank/healer queue).

As nice as it would be to just throw different roles out, we already have precedent that it’s not much different. Personally though, I wouldn’t mind not having to switch my class to queue as that class but it probably isn’t worth the coding effort for the team. But if they could QoL the queue on anything, I’d just ask for that.