Having worked in research for a long time, once you've invested a lot of time an effort into some line of work, you're always looking for some way to continue, spin, or create the least amount of iterative difference in previous works to find funding or push an acceptable paper out. That's just the nature of the environment. Even if most the world moves on from something, the effort to change tracks is often higher than continuing down less promising routes.

Now, there is some value in continued work that ignores consensus or popularity. Consensus doesn't mean absolute certainty and historically big leaps have been made in areas people consider lost causes or wastes of time pursing. So, its good that we don't abandon searching the knowledge spaces entirely, but I will say that's often not the driving motive. It has more to do with careers and putting food on the table, such is the ecosystem that is research. LK99 won't disappear for quite awhile and people will continue novel research in the area.