I think the longer respawn times promote better game play. Face it, if you're respawning practically instantly, there's almost no consequence for dying. You just blindly rush into the action, guns blazing, and hope to get a kill or two before you die and respawn again.
Perhaps a potential way to balance it out would be to have increasing respawn times. Either the more you die, or the further along the round is, the longer the respawn time gets, so rounds could actually end on the short respawn servers, and there would be more of a consequence for dying repeatedly.