For Archer, it's a strange thing to have a healing limit break, but for Bards it actually make sense. Their support is there to buff in times of need, not when you want it on demand. An instant raise has saved many parties I have been in that were able to get the job finished, and that's what I picture Bards as being there for. It even says as much in the official description.

I would expect that a ranged based LB will be added in when more ranged physical classes come into play, as the idea of a raise won't fit all kinds of ranged roles. Whilst Archer/Bard is the only one of it's kind in the game, this has obviously been a balance/design decision rather than just lumped on because.