C'mon, now. Not everyone is stupid, and not everyone are dicks, either. If not everyone's going to work together, then why are Horde modes popular? People are willing to work together under the right circumstances.
Otherwise, games like Left 4 Dead, Ghostbusters, MAG, SOCOM, Borderlands... They wouldn't have been popular at all. Not to mention the rise of co-op in games like Halo, Call of Duty, Portal 2, and the amount of teamwork in MMOs. Many people do like the chance to work together in teams, to work towards a common goal.
As far as the "outmatching," it could be easily adjusted. Give the smaller team some superior weaponry/armor/perks/etc, weaken down the opposition, and increase their spawn count. That way, both sides would still have to work together so as not to get themselves killed, but the tactics would be different on both sides of the coin.
And for the two guys trying to cross the graveyard - It was a possibility. Perhaps it's a random opportunity that the game throws your way, and the reward isn't necessarily a "win" for your team, but instead is a huge individual XP payout, and a unique trophy/tag customization.
Thinking outside the box is what brought along every innovation in gaming. There are ways to make things different, fair, and fun - And not just be simple team deathmatch every single time. Besides, these are just ideas. I highly doubt that Infinity Ward is taking notes.
But it would be nice to see some interesting new modes in Call of Duty for a change.