the ranged LB in pvp is such garbage. It has so many issues that make ranged damage dealers not even consider using it. A lot of this applies to PvE as well but that's not my focus right now.
First issue: aiming. Having to have a target makes it really hard to aim the LB where you want it to go, as your initial target may move and you have to adjust to get maximum effectiveness out of the LB which can be very difficult with a constantly moving target. It's even worse for a controller user as targeting is terrible and usually ends up targeting something behind you rather than what you're looking at. It would be much better if the LB had a small target circle (like the one for placing a pet) and the LB will fire in a line from you in the direction that you placed the circle.
Second issue: speed. The LB goes off sooo slowly, for Mage it's fine for it to be slow because the large radius makes it difficult to get out of. But the time it takes for the ranged LB to go off with their thin line AoE, you can basically side step it and do a dance before it goes off. I wouldn't say it needs to be instant, but it definitely needs to be faster than it is.
Third issue: damage. Combined with the above two issues the damage if you actually hit something is appalling, Mage LB is about 50% hp in one hit. With ranged LB you'd probably have done more damage just using your AoE skills in the time it takes to use the LB, it just does nothing.
Fourth issue: basically a culmination of all of the above but, animation lock, you get locked in place for so long, everything you target sees that LB line and goes "oh a MCH/BRD is LBing, thank you for the convenient trail that leads me back to you where you're stuck in place and defenceless, let me just sidestep out of it and come murder you with my 10 other friends you tried to target, good thing you're right next to us so you'd actually be able to hit something with it even though you're a ranged damage dealer!". I can't really think of a way to deal with this other than fix all the other issues so this won't be a problem since all LB's have animation lock, but they can actually do something with theirs that makes it worth getting locked in place for.