Why is there a bias against MP only games?

[Goatseye]

Gamers on internet have a bias against MP only games. Although a minority, they're a good size of forum dwellers.

Some of the justification are that:

1.   there's not enough content to justify a $60 tag, 
2.   there is no story or some form of campaign, 
3.   they're mostly aimed at dudebros
4.   etc,...

Give me some argument for and against these type of games. And if you can find arguments against single player only games, drop it here.