Don't listen to the straw men who play the "kb and mouse is better anyway" instead of answering your question.
I own both versions and let me tell you, playing on the 360 is a joy and exactly how it is meant to be played.
If I am in the middle of a fire fight, I don't want to dive for the health key, or the plasmid up/down key as the Big Sister is throwing me around like a rag doll. I doubt in real life, a Big Daddy would stop in a middle of a fight, and flip through a deck of cards to select a weapon and ammo combo.
2K could have easily solved the situation.
Either add the gamepad functionality for those that want it, can use it. Add a radial system to the keyboard controls, so the game pauses while you select your weapon/plasmid (SP only)
2K refused to do either and seeing how they handled the DLC, it is clear they don't care.