I think McCoy gets too much guff here about his attitude. Anwar even called him racist towards Spock (and I know he's not the first person to say that)! Personally, I've always found his attitude endearing. He's stubborn, grumpy, and confrontational, but I just chalk that up to being passionate about his beliefs, and I respect that.
He's a bit of a hypochondriac and very argumentative, but I never found it grating and despite his curmudgeon ways, I never found him mean-spirited. At his core, I think he's a good person who's always wound up because he cares. The scene where McCoy and Kirk first meet in the new Star Trek was one of my favourites in the movie because I think it perfectly showed how endearing McCoy's conviction about his beliefs is.
All his ranting about the dangers of space travel just served to highlight how passionate he is and concerned for his safety and everyone else's. Listen to his "there is only one Kirk" dialog in "Balance of Terror". He almost sounds like he's just lecturing, but he's actually showing how deeply he cares for his friend's well-being.
I disagree slightly here,
Too Much - I think McCoy almost always gets a full pass for his behavior, even questionable behavior, just because most people like him so much. People such as
Anwar,
Gotham Central and me are definitely in the minority, and a fairly small minority at that. Most TOS fans love McCoy. I sometimes wish I did, but I just don't. I can appreciate, most of the time, his role in the series, but there are episodes in which what I see as his shortcomings as a character really come out, and this episode is one of them.
But don't worry - you're definitely in the majority here.