I'm not even particularly good at shooters, they just don't require the level of skill you seem to think they do. Whether or not you choose to believe me, that is exactly what I do in the campaign mode for shooters: I use little to no cover and just strafe around the room shooting at whatever is shooting at me and, nine times out of ten I'll clear the room with little to no difficulty. If I was playing on the hardest difficultly I wouldn't be able to use this technique but, likewise, if you played Bayonetta on it's hardest setting there is absolutely no way you could beat it by just mashing the attack button; you have to block and parry, getting into rhythm with the enemy's movements.
And as for your comments about 2D fighters, you are talking out of your arse. First of all their control schemes are far more basic --most of them just require you to have rhythm-- than some hack and slash games (mainly DMC and Bayonetta) and, as Yahtzee has pointed out in ZP before, beat-em ups have some of the biggest cases for a game that you can spend weeks mastering and still get beaten by someone spamming the same attacks over and over, (see: Soul Calibur's hilarious ring-out bullshit.)
I didn't say a game could be completed wrongly, but nice try misquoting me to try and discredit my point. What I said was that there are right ways and wrong ways to play certain games. If you want to just blindly button bash your way through action games then, yeah, you'll probably do alright on most normal difficulties, but you won't get the best scores or ranks, and that is what makes these games really popular; taking the time to master the subtle nuances of the control systems and executing huge chains of attack, racking up huge combos and killing with skill as opposed to blindly swinging your weapon in every direction.
If you choose not to play the game in this way, then that's fine you'll probably get by okay, but understand there is a world of difference between all of the games being the same and you choosing to play them all the same way.
I don't know how many more times I'll need to say this but I played Battlefield just like I play CoD (and just like I play every other shooter) and I had no problems. I'm starting to suspect you're just not very good at games.