Well, people want something that the phys ranged offers.
The role bonus. For the same reason you take caster or melees with you.

If it would not be so important, then they might go with double/double roles.

And I don't know a single phys ranged player who felt forced to play that role.
The gameplay of the phys ranged are good enough that people want to play them and that there is no shortage of these players.

If we talk about raw DMG output then they might need a small buff, at least the MCH needs that.
But DMG is not really that important.
Like, i play PLD and don't complain about being the lowest DMG tank because I do not get excluded anywhere and I really enjoy the gameplay of that class.