The enemy types are barely the complaint. It's more how you deal with them. In this case, you rush at them, strong attack and kill them with a few quick blows. This quickly grew repetitive for me.
I appreciate your opinion, but again, the comparison to Modern Warfare 2 was within the variety of the gameplay as a whole. There was a lot more than just walking into an area and shooting people. Players needed to use different techniques and strategies to conquer the varying terrain. In many cases, the objectives forced a change in gameplay.
Red Steel 2 never really did that, and honestly slashing with the sword grew quite boring for me fairly quickly, even though it worked nearly flawlessly.