I was playing tonight and I had 4 consecutive people ragequit on me, so I thought I'd share my feelings.
To me, there are two levels of ragequitting:
1) Raqequitting within the first 1-3 turns: to me, this is completely acceptable. If you enter a fight and are completely overmatched against your opponent OR you enter a fight and just completely misread the battle or get blown away right off the bat, I'm completely cool with abandoning ship. I don't mind if people do it to me, and I have done it before (and will do it again). The point of battling is to have FUN, and if a battle is out of hand from the get-go... well, that isn't fun.
2) Ragequitting at the endgame or right after the last pokemon faints. THIS is obnoxious, and I won't and haven't do this one. If a battle is fair and fun and well-played, I'm more than happy to let my opponent have a win. It gets frustrating when others do this to me because, a lot of times, I just had a battle that I want to save a video of so I can watch again and post for my friends to see.
So, to me, it depends where the battle is when the ragequit happens. I don't think they're all created equal.
P.S. Can I say that, after having read a few posts here, I'm moderately offended. A lot of people say stuff like "I NEVER quit! Unless I'm facing a hacked team with all shiny flawless pokemon!" Well I only use shiny flawless pokemon on Wi-Fi, and they are all legit. I spent a lot of time trading for them on here and removing the ones I find to be hacks, and I EV trained them myself. Don't assume just because someone has nice things that they are hacks.