I have to say, I agree; I've always been an advocate of games being predominantly single-player oriented, and find that when games have both components, the single player campaign often feels diluted due to the amount of focus placed on multiplayer (prime examples of this are Halo 3 and Modern Warfare 2). Some people simply don't want to play multiplayer. I avoid multiplayer on Xbox Live like it's the plague; if it's not twelve year old boys with unbroken voices sqealing in your ear about how much you suck, it's the racists and bigots spouting crap through their microphones (and there's evidence of it on YouTube). I do play on TF2 on PC quite often, simply because the community's generally more pleasant, the gameplay isn't always frustrating, and it seems like the only FPS multiplayer game to not take itself too seriously.
Getting into any established multiplayer game can seem like trying to break into an exclusive club, or the Stonecutters; having a low level to your name can essentially make you look like you've escaped from a leper colony and no one dare come near you, so you find yourself on a solitary trudge wondering "where is this experience everyone was talking about?".
Unfortunately, the fact is that multiplayer the vast majority of the time isn't spoiled by the gameplay, but the people you PLAY with; and it's even more crushing when you find out one of your closest friend plays like a giant wanker when they're online.