Perpetrators: THQ, 2K Games, Rockstar
Worst Example: Bioshock 2
Making a good multiplayer experience is one of the hardest things a developer can ever be tasked with doing. It takes significant resources, time, and planning to execute correctly and a majority of the time, most of the publishers aren't willing to devote enough of any of that to make it work. Instead, they'll either outsource that component of the game to another company that'll create a disjointed experience from the (usually better) single player game or pull folks off the campaign to work on maps or something.
Most of the time, this doesn't result in additional benefits to the consumer, doesn't have them keep their games any longer before trading them in, and very often pulls resources away from making the best part of the game as good as possible.
The Solution: Don't fear making single-player only games.