only problem with arena shooters is single player is pretty shallow. you also have pretty much two groups of players. the hardcore crowd who dominate matches. casuals who get dominated and then drop out of the game. the learning curve is too high for a lot of people and they lose interest because it's no fun getting dominated.
with arena shooters you have to have good twitch aim, know the weapons especially if they're not hit scan, know the levels, timing of power ups, higher level movement (strafe jumping, bunny hopping, etc), sounds. with other games like battlefield, bf4 you don't have to be a good fragger to still do well. even with a game like cod you have perks you can take advantage of.
we need some more threewave ctf or clan arena.