The only online game I play on a regular basis is Team Fortress 2, so the benefits of team-switching just before the end of the round might well be lost on me, but I think it smacks of cowardice, really. Besides, aren't last stands against a superior foe far more exciting than simply defending until a round ends? Or, if you're playing team deathmatch, being the last man standing? Maybe I'm the only one who enjoys such things.