I have many valid reasons to complain about the game, despite having never bought it because I saw through the formula in half on hour with the beta. I've continued to talk with people I know about their experiences with the game, read about the details of how the gameplay progresses, watch videos, etc, so I'm well aware of how the whole damn game works and yes everything I thought about the game from the first half hour seems to remain true throughout. I don't need to hear about how my opinion isn't valid because I didn't give it enough of a chance. Now that I've covered that base, here's why it's perfectly legitimate for me to be vocally upset about the game.
1. I expected more of Blizzard. They are the organization that popularized the genre and have 16 years of experience working with it. They have probably the most resources to invest in development out of any studio in the world. It had been roughly 11 years since the last release in the series, and we know that they had been actively developing Diablo 3 for at least 6 of those. There was every indication possible to believe that this would be a groundbreaking game, and yet not a single aspect of the final product gives me the impression that it was made by people who knew or cared about what they were doing. No, not even the graphics.
2. I don't like being pressured into spending time and money on doing something I don't like, just to be able to do something with friends. When most of your friends are gamers and playing games with them is what you do most nights after work, major multiplayer titles have a distinct effect on your social life.
3. The success of major AAA titles like this factors very, very heavily into design trends for the entire industry. Yeah, I can simply choose not to play it, but that doesn't stop the success of the game from bleeding into everything else that I will end up playing from here on. More games are going to embrace the always online model. More games are going to feel safe about further dumbing down their game design. There is more at stake than simply whether or not I am happy with or choose to play this specific game. It makes a lot of sense from a long-term perspective for me to discourage people from rewarding Blizzard for their behavior.
So I fail to see how it's not legitimate for me to hold these opinions or to be vocal about them.
I'm not trying to ruin anybody's fun or make anyone feel bad for buying or playing the game, but I don't think there's anything wrong with making comment occasionally when a specific of the game design is being discussed or joining in when people are already venting.