Le *sigh*
I've played and replayed many of the same games Sterling mentions, and hell yes, I'm all for devs putting their time and effort into making good, solid single-player campaigns with tightly written stories and deep, enjoyable gameplay. Heaven knows it can be hard enough finding a handful of people to play a multiplayer game with, let alone people who will be enjoyable to play a multiplayer game with, without the game you're trying to find those players for being Cooking Mama 6: Decorative Frosting Cannon Free-For-All.
But I really don't feel this kind of vitriol is remotely warranted for people who feel they get more out of their games for having multiplayer or multiple endings or New Game+ modes. When all is said and done, this is a matter of taste and opinion, not something that one can simply sneeringly say "you're wrong" about without looking like a total wanker.
It's fair to point out to people with this mindset if they demanded multiplayer in Bioshock 2 and then griped about it or never played it; it's certainly not unreasonable to wonder if the inclusion of multiplayer diverts resources that would have been better allocated to the "real" game if such seems to have been the arrangement. But while we're on the subject, we might spare a thought to the developers who decided to spend their time and money that way, and recognize that there are other factors in play than just a certain kind of message board complainer. Extending gameplay by these mean is also one more hedge against the bugbear of the used games market, and in the case of multiplayer one more excuse to get players online, and thus one more way to collect information about the player base.
More thinking, less sneering, Jim.