Disagree about team having a 'mission statement'. The problem is that whenever they put together a team for a specific purpose, it ends up being an assasination squad. X-Force was meant to track Cable and Hope, but it doesn't seem to be very smart to keep everyone capable of tracking them in the same mission. Surely it would've been better to put together several teams consisting of: a tracker, a teleporter, a telepath (to coordinate), and a few people for muscle.
Besides, the right concept could put characters into place where they'd seem more important and useful. We can get a mutant espionage book starring Cyclops running it secretly from prison, Forge as the gadget guy, Cypher and Prodigy as Bourne-esque agents, Gambit or Storm (less likely) with the thief angle, and a teleporter.
Ok, can't say people would read those characters or concept, but I'd rather have that than generic mutant team 4.