The basic gist is that buffs and nerfs are going to try to address aspects of popularity in consideration toward success rates and not that success rates determine change by itself.
The point of offering variety is for that variety to matter. So in the case of select heroes that are overly picked, but otherwise decent (or conditional) talent variety, they may see generic nerfs; if a talent is overly picked, then it might see a nerf, etc etc.
Basic gist is to have variety matter. Regardless of some of the changes or shifts on staff, or visible types of changes, that goal has been fairly consistent for a few years now.