For any type of game that mainly focuses on competitive or cooperative aspects of gameplay, such as fighting games, sports / racing, most shooters (but not all), and any type of role playing or strategy game that isn't a story driven single player affair, the online components of these genres are crucial to their success and longevity.

I do question the obvious, particularly when large numbers seem to mindlessly going somewhere on what looks like to me as mindlessly assuming things.  For me, I have yet to find online multiplayer mattering to me.  I am also highly aware of how online fails to really meet the social needs of people in a meaninful way.  What I do see it is serves a use as a providing humans instead of bots.  However, if you do have friends, it is an alternative way to play, particularly if not local.  BUT, it gets spun as a MUST HAVE, as I saw in a recent Bonus Round video where one of the media types was bashing Nintendo for being so far behind Sony and Microsoft on things.  It is presumptively pushed as the killer and essential feature, and I question that.  You see cases, like with Spec Ops: The Line, where online multiplayer was ramrodded through.

How about having more aysnchronous online multiplayer and playing for points and leaderboards?  What I saw is this feature had been taken out of games, and it was a feature important to me trying to run events.  How about something pretty much different?

Offline splitscreen is dying because of the push for multiplayer online. A very rare title to feature this, and bots, in an FPS, is Perfect Dark Zero, believe it or not.

Because online multiplayer is seen as critical, they are taking away the offline multiplayer.  Online multiplayer is seen as what matters.  It is seen as so important and critical, Titanfall is featuring this, and this alone.  I also see no word of Titanfall featuring split screen either.

Because having real life friends is so last gen...:p

Yeah, who needs stuff like this, when you have your own online personal network!

Because humans are way more sophisticated than any AI.

When you think about it, that's really the issue with a lot of games. The challenge doesn't really come from the enemy being more skilled than you, but always something I consider to be "cheap".

In the Total War series for example, the AI can't manage finance for shit, so they're given free money. In a lot of shooters, you're fighting alone against numerous enemies. Bosses have special abilities, etc.

The qualities of a good multiplayer is what makes multiplayer more fun than singleplayer IMO:

1) Balance
2) Options

Balance forces everyone on the same level field, and rewards skill over stats. Options makes multiplayer dynamic and fresh with every game.

Whereas in single player there's one optimal strategy (get X item, level up to this, follow this exact path), multiplayer is a constant cat and mouse game.

Note I said ONLINE multiplayer.  And I was primarily talking about matchmaking systems where you get matched up with people you don't even know.  I did tip a hat to cases where you are long distance from people you know and it is difficult to get together.  As I said:

I wil add here, if you have friends remotely, it is nice to be able to play with them.  But beyond this, I don't get it.

It makes a game 1000x better and more enjoyable (assuming it's done right) and adds near infinite replay value.

Hell, I'm still playing Gears 3 online on a regular basis. Would have sold the game long ago if it didn't have it.

The same reason why people play video games to begin with, because it's fun.

I get what the OP is saying. I too mainly enjoy single player games.

The online element does add to the game but it isn't the be all and end all of the game if it doesn't have one. provided the single player game is good.