2 melee 2 ranged standard

[Ayche]

It's a bad idea from a fight design standpoint. 2/2/2/2 design is built around the idea that there are going to be four jobs that are obligate melee ranged, so you're constrained to resolve mechanics in a way that let four players maintain contact with the boss. If you add in an additional ranged as 'fake melee', then they can be off in another arena while the remaining three melee range jobs have comfy access to the boss. You're essentially bypassing constraints that designers can place on mechanics.

Constraints are to the benefit of the players too. A sudden shift in the paradigm where one wing or even one raid encounter could no longer fit 4 melee roles into it would just create an unnecessary trap for the player base. And in the situation where all four melee roles cannot be easily solved for good uptime, you can always punt the paladin or any tank to the sidelines and make them do some ranged attacks in the corner.

In all honesty, it only sounds interesting as a thought experiment and probably not very exciting to play. Like I can also think about "what if we made a fight where a healer is never allowed to be near to their party, that would make using aoe heals so much harder!" but would that actually be fun?