I have maybe 3 or 4 of them. I usually buy my games on sales so its still worth it to me even if they are short.  But I also buy Battlefield, and BFBC2, Halo series, many other FPS, too many to name. I have only played Halo online, and I play CoD split screen with my buddy

Edit: I may still pick up that CoD that has the Zombie campaign, soley for the campaign. Can't remember if it was the last one or the one before that.

To be honest I feel they somewhat need it, if purely from a marketing standpoint. Call of Duty is always marketed as some kind of massive 'block buster movie scale' video game. Take away the single player and you can't really call it that any more. It's just a game about shooting people on various maps.

If you enjoy them then that's cool.

Just would like to point out that Zombies mode in BO2 is not actually a "campaign". I think that's a common misnomer used for it.

The mode that is referred to as campaign is called "tranzit" and essentially it's just survival mode from previous games but on a very large map. A lot of people who haven't played zombies before went into it thinking it will have some kind of story that will be told to them in the normal sense. This is not the case. Although there is a story, it is told through a sequence of VERY cryptic events (essentially easter eggs) and it carries on heavily from the original BO where you will have to have played all the DLC zombies maps and completed their easter eggs to be able to understand what is going on here.

So essentially I would be careful about that since it can be somewhat confusing. If you want to know what the "campaign" is REALLY like in tranzit mode, I'd suggest you check out the "tower of babble achievement guide" on youtube. Essentially you get an achievement for completing the whole thing. You need 4 people to complete it and you have to essentially do it in one sitting, otherwise it resets. It took me like one whole night (about 10 hours) to complete with 4 friends (although it was mainly because I was having trouble getting EMP grenades lol) and it's actually fun because you have to really have some teamwork going.

For one thing, like Zekkyou said, it's really hard to hype a mainstream military FPS without single player. CoD just wouldn't make nearly the splash at E3 if the guys on stage just showed us a quick game of deathmatch.

Also, the campaign can be really enjoyable, even though the story isn't Shakespeare. I still remember how riveted I was during the SP of CoD4, and I don't think any military FPS since has quite had a setpiece on par with the "Shock and Awe" segment, but I think that's limited only by developers' imaginations. If single player for such games were scrapped, those devs would never get the chance.

Well if the Crytek CEO has his way then it will be gone from FPS lol. Honestly, you probably could drop it, and it would sell like hot cakes. You could probably drop military FPS altogether, and maybe we get some more variety in the game market :).