I was glad to see that go, too. But the way they did it was very natural, considering that McCoy actually had Spock's katra in him, and then, later, showed clear worry for Spock in Trek IV. You could see that it was tearing him up inside to see the reborn Spock rejecting--or seeming not to understand--the human side he'd come to know over time. I think that was a real maturing event for McCoy as well as for Spock: it's hard to make mean comments about someone whom you have linked with in that way.