I can play a single player campaign over and over especially if the gameplay is good. I think the problem is that most gamers won't do this after they finish a game. They play through it once on easy/normal difficulty or just long enough to get the trophies/achievements and move on. Most I've asked on why they can't play a game again and they all say the same thing, "I already know what's going to happen, story, etc." Which is strange to me cause games are about the gameplay and how much fun you have playing the game not, "Oh I want to see the story!" I think the single player games need to do what most of the games back in the 8-bit days did and add a score mechanic. Players get a certain number of lives and leaderboards for chasing high scores. This at least for some could create a reason to play it over and over to get better and improve your score.

Most people I know that won't go through single player campaigns again usually play sports games and online shooters over and over. If you think about those it's all about stats progressing through a sports season or K/D win/loss stats and progressing to new levels on online shooters. They're games that are played over and over basically for stats. Im willing to bet if these games didn't have a stat tracking system people wouldn't play them as long. Which again I think might be one reason single player games don't get as many play throughs. Think about a game like Borderlands that has a stat tracking system with new levels unlocking etc. That's a game that has gotten multiple playthroughs basically cause of the stat tracking and it gives you that "I wanna come back and progress" feeling.

The only time I play online multiplayer is on some racing games. GT6 and NFS most wanted most recently. (Didn't bother with online in NFS: Rivals)

Single player or local multiplayer with the kids is how I play everything else. I usually play twice through a good campaign. Second time on easy to see the story flowing better and explore what I missed without worrying about health and ammo. ND games are an exception where I do another play-through on hard.

I briefly touched Far cry 3 online coop, it fell far short from the experience the rest of the game provides. Before that Uncharted 2 mp, tried it one night, didn't like it. Killzone 2 couple of nights. Didn't bother with Killzone 3 mp. The only online experience that kept me interested for a few weeks was Resistance 2 8 player coop. And as Mikeanheath just said, that was basically for the leveling up, not sure if I actually enjoyed it :/

Actually I did use co-op in Dark souls to get by bosses and get easy souls. More out of necessity than fun, the unwanted invasions were a pain and some of the boss fights were ruined by the unmatched co-op pairing.
Online multiplayer worked for me in Journey, that's something at least.

Same to me.

Online play is great, for sure, it´s nice to have more than just the regular main/story mode. But take the example of Need For Speed Most Wanted. I never imagined a racing game withou split screen.  I was really really dissapointed when I got this game and noticed that it doesn´t have local multiplayer, only online!   Where I live fast internet connections are not available and I was expecting this game to be one to use during my gaming parties with friends.  Dissapointing.   

I always thought that videogames were a great way to gather people together, but it seems that companies don´t think like that, or don´t want them to be like that

I disagree depending on the case. I feel for shooters, and racing games, especially, online multiplayer or LAN is the way to go. Splitscreen in my person opinion is never really that fun, it always feels too clustered and the other player screens get really distracting.

Local multiplayer is not an easy thing to do, for some games it's simple, like fighting games, but I was playing Mario 3D Worlds with a friend yesterday and it just felt a lot more frustrating than it needed to be, which is why I assume they added the bubble function. But the bubble I think is just a band-aid to the problem as opposed to acutally fixing the issues I have with the LM. I think in general that's the overall problem for most games unless you want to structure your entire game around LM, like an arcade game, you have to implement compromises.

Feels like we get a new SP vs. MP thread every week.

Anyway, I prefer SP. Nothing against MP either but it usually doesn't offer a very interesting experience.

I don't get why some people hate MP so much now. I'll always play both SP and MP. I don't see why you'd do anything else. 

Because tacked-on multiplayer is just a waste of time. It's usually a very shallow experience, feeling like something you've experienced a thousand times before. Only properly designed multiplayer modes are worth any time, and even then people might just not like the competitive aspect. Co-op might be more fun even to people that don't generally like MP very much but in the end, it's still usually a shallower experience than SP.

So now we're assuming all multiplayer is just tacked on? And just because someone doesn't like MP as much as single player doesn't mean he or she has the right to say "Good" whenever they hear that a game doesn't have multiplayer. I rarely hear multiplayer people say single player is a waste of time. Why is it ok for single player people to say it? I love multiplayer and single player. I don't see why people (especially single player elitists) can't just accept that both are great. 

No, we're not assuming so. You said you don't see why people don't play both SP and MP and I provided some reasons why people might not want to play MP or why people might strongly prefer SP. And yes, people do have the right to say 'good' whenever they hear a game has no MP. Whether it's actually good or not is debatable but they definitely have the right to say so. And I don't know where you've been but I've definitely heard enough dissing of SP here. Call of Duty would probably be a good example of that: "I don't see why anyone would play CoD for SP." And the fact is, 'great' is a very subjective word in this case so you can't just say that both SP and MP are great and expect people to think the same way as you do - they have the right to disagree. Of course similarly everyone has the right to not like SP and say it aloud.

100% agree.