Evolution doesn't optimize for benefits to the individual. If it did, we'd all regenerate like salamanders.

That any sort of cell therapy or signaling change works at all to improve health is indicative that the standard issue biochemistry in mammals is suboptimal.

The risk from this sort of thing, like all efforts to change cell behavior towards greater tissue maintenance, is cancer. One of the most interesting aspects of the whole field of regenerative medicine is the degree to which cancer hasn't emerged, however. There seems to be considerable leeway for crude methods to improve regeneration to work without large increases in cancer risk.