Possible solutions:
Perhaps introduction of character states to save a couple of predefined roles is in order.
Say up to 3 per character, and if you want to rewrite one you have to pay.
Of course pay for each slot and only available in your HQ.
The one click re-roll you want with the limited rerolling I want.
Seems like I'm the only one, but I really like this idea, it solves the problem of certain roles going offline and ruining composition, while also allowing the feeling of fulfilling a role and having an "identity" in terms of an RPG like Shangalar spoke about.
Even if it was just a second (already selected) character preset that a player could switch to at base. That way a player has his main class that he enjoys the playstyle of the most while being able to change roles quickly and to great effect. (E.G. If someone played a sniper as his main, he may want a melee tank as his second "profile", or a sneaker may want a tank burster as his second profile, keeping options open for quick and easy team composition switch ups.
Don't get me wrong I love free rerolls, and this server has the best reroll system by far, so I do feel a bit like, if it ain't broke don't fix it but, it is pretty silly being able to morph into whatever you feel whenever you feel with no restriction.