So recently, I've read a couple of blogs that discuss the teamwork aspect of role-playing games. It got me thinking...
D&D was the first role-playing game, and teamwork is definitely built into the game. The character classes are meant to segment party roles and contributions: the magic-user can do really nasty things but has low hp and no armor or combat ability. He relies on the fighter to protect him. Thieves and halflings were the sneaky characters, able to ambush and scout. (One they were added, that is) The assumed goal of the game was exploration, dungeon delving, and the objective in any module you might be running. These goals were for the entire party. The conceit of D&D was that the characters were in fact a party and did things as a party.
Since D&D, there have been untold numbers of rpgs published, and it seems to me that many published in the 90's and now are more heavily focused on individual character goals. I think White Wolf games are especially written this way. Perhaps the champion being old Wraith: the Oblivion, in which your character's desires and unfulfilled needs were stats with mechanical significance on the game play. Another example would be The Riddle of Steel, a (now apparently defunct) indie fantasy game where you get bonus dice if you are acting according to your characters Passion, Destiny, etc. In addition, since most games now seem to be genres other than swords and sorcery, the adventuring party concept is a bit obsolete, and most game books seem to just advise the GM to find some way to rope the characters into getting and staying together. Hell, some game books actually have to devote sections to how to do just that. There are obviously exceptions to this, (most superhero rpgs assume an adventuring party of sorts, modeled after super teams like the X-Men or the Avengers or the Justice League or whatnot) but the underlying assumption in many games I've played in the past decade is "you design the exact character you want and let the GM worry about keeping you together."
I'm sure many of us have played in or run campaigns where the only reason the characters are staying together are because the players are all playing the same game. In some cases, the game setting actually enforces this: if you've got it, take a look at Mage: the Ascension 2nd edition. There are nine magical traditions the characters can belong to (well, more than that if the ST wants to break the default campaign mode, but let's not split hairs) and none of them fucking like each other. If you read through each group, it dislikes, distrusts, totally hates, or barely tolerates each of the other groups. Ditto for Vampire the Masquerade. Now, in your classless system, you can design characters that don't need each other, plus the core book says they don't like each other.
The result? Most White Wolf games I've been in, with one or two exceptions, have crumbled as the party splintered into factions or just outright refuse to work with one another. I realize that any element of the setting can be rewritten or ignored at my option, but I think this setup does instill players with certain assumptions about how the game is played, especially if this kind of game is their first experience with gaming. (Tangent: I'd say Vampire is the second most common "first game" among gamers I've known, the most common being some incarnation of D&D.)
I think it's exacerbated by the fact that, by default, the characters sort of have to stay together because otherwise the GM is running two or three or more mini-campaigns at the same time, resulting in sections of the group sitting idle while the others get their turn interacting with the GM.
I've also found that, across a variety of gaming circles, this approach to gaming gets the players thinking that the campaign is a story about their character, with the other players' characters being supporting cast. When every player around a table gets thinking that way, that-sa no good for anyone involved. (And some games these days actively emulate the feel of a TV show or movie, which further encourages these assumptions.) Unless the group is specifically gunning for a competitive campaign where the characters are supposed to be opposing one another, the style of competing agendas is nobody's friend.
Now maybe it seems like I'm up on a soapbox, but that's not my intention. This entry isn't supposed to be me preaching Old School Forever or the One True Way or What's Wrong With the Hobby Today or Some Other Concept That Gets Wrongfully Capitalized. Rather, I'm just sharing my experiences in having played and run these games with a variety of players and GMs. If you want to play competitively, that's coo'. If you dig games that don't force the assumption of shared goals on the players a la dungeon delvin' D&D, gravy. I've just noticed that campaigns where the characters don't have a shared goal or mission, but are rather set upon a GM-created plot (or even a sandbox) with a laundry list of character-exclusive goals or competing agendas tends to 1.) not be very enjoyable after awhile, and 2.) tends to fall apart without any satisfactory closure. Your mileage, as they say, may vary.