Generally speaking, yes, melee DPS has limit break priority, followed by caster DPS if there's no melee DPS, simply to deal damage and get bosses done faster.

Otherwise, limit breaks are chosen for situational value - Healer's limit break in 8-mans is used to save the party if things have gone horribly wrong (100% HP/MP recovery and revive on the entire party at rank 3). Tank's limit break is used in very specific fights for very specific reasons (Dealing with a mechanic during Ultima's Bane). Caster LB is a clearing ability. There are fights where it's useful, both before and after 50. As mentioned, Haukke Manor (L28 dungeon)'s final boss has a part where she summons three adds at once - it's the hardest point during that fight. most of the uses of it though are for hard or extreme 8-man primals, where multi-target burst damage is extremely valuable.