In 4 mans, dps limit break might save 3-6 seconds on the run, even if it's a caster lb on a large pull (provided people know how to aoe)
In story mode raids, or primals, the fights are adjusted to be able to just faceroll it anyway, so people don't stress lb usage as much.

Then into savage/extreme/ultimate, the limit break is required in certain spots, by different roles to complete the mechanic, or make a mechanic easier, so usage then becomes dictated more by the fight than preference to do a big hit of damage.

People also generally don't like doing it in other situations because it can greatly impact your rotation.