Man, that stuff should just be instant death. The only way QTEs should be involved, is if it's a co-op sequence. Would have been awesome if they made it like the movie. You have a Facehugger jump at you, and got seconds left, to have another player aid you, to pull it off, and throw it a safe distance away, so you can shoot it.
And regular Aliens? If it were up to me, I would have added a context sensitive action. By yourself, you don't have a chance. The Alien is on you and mauls you till your health depletes completely. Another player can get it off, but only by using his entire weight and drop kicking it off you. But the action causes you to end up on the ground as well. Non of that stupid pushing it off or pistol whipping it.