Requiring bnet login to play Starcraft 2 single player was the nail in the coffin for me. I don't think I bought a single blizzard product after that, though I did keep paying my WoW sub until just after sunwell and I burned out.

You could see the way the wind was blowing and the company flipped from creating great gaming experiences to "how can we best corral these losers to shove our 'important marketing messages' down their throats".