I never ragequit mid-match either. I've ragequit plenty of times BETWEEN matches, but I never do it until the match is over (unless it's over something that makes it completely unplayable, like horrible lag or such).
That's interesting. I only really play Starcraft 2 online, but at least in that game I prefer it when my enemies quit when they know they have no chance, and I do the same (though always prefaced with a sincere "gg" before I do), cause I feel like slugging it out to the end is kind of a waste of time when the result is predetermined. I look at it kind of like chess: you only play till checkmate, you don't actually take the king. So at least when I do that I'm not ragequitting, I'm just acknowledging that I've lost and moving on to my next match.
Though I will say that I find it irritating when people do it too early, like the very instant you get a hit on one of their buildings. When I do it it's usually like all my production facilities are completely destroyed and they're pounding on my resource operation, and I have no hope of reinforcements.
Also though it's less of an issue in Starcraft 2 for people who DO want to finish wiping out the base, cause you can hit "keep playing" after the victory thing pops up.