Limit break is underpowered simple as that. In ARR it was really good but HW player power outshined it. SB there's no reason to use it now. The long cast time doesn't help with aoe mechanics flying all over the place and the flashy graphics don't line up witht he shit damage. In cases as say like a Dragoon using it, that kills my BotD meter and losing that is devastating to dps overall. So it's rare that it's safe to use LB for a very miminal gain.

Simple fix, increase it's power and while channeling/in animation it freezes all your buff timers. Put in something so you can't abuse it we're good. Otherwise unless it's scripted there's no point in LB use.