I don't really care if they lose games in the majors, if those losses pay off for the next five years. I do care if they are hurting Kingery's development, but I don't know if the trial by fire approach is necessarily a bad thing, and keeping him at SS instead of moving him around again is kind of the kid gloves approach. Seems to me the real story (as you note with Machado reference) is that Crawford's future might be at 3B, Franco is done, and Kingery will eventually go back to super-utility and/or 2B. It also seems less likely they will make a deadline deal for a 3B (or Machado) 'cause they just want these guys to play (Williams, Hoskins, and Altherr included) unless or until they aren't part of the future.
It is, however, a bit of a shame if they're not willing to send down Kingery just because of optics; contract or no contract he would hardly be the first promising prospect to have to go back down. But putting him out there everyday isn't really hurting the team any more than playing Franco or Walding would.