This provides some official recognition to those old players.
I've seen a few people, both white and black, opposing this, but my general sense is most people are on board with it.
We don't really know how to directly compare the two sets of records.
We know some of the best players were in the Negro League, so obviously MLB players didn't face all the greatest players of their era. At the same time, some of the white players were also among the best (even if only because there was a bigger talent pool to draw from). So nobody faced all the best talent.
So just combining them, however awkwardly, may be as reasonably good as we can do. And if it provides more recognition for players who deserve it, it's for the good.