I think it's good that the NPC's can punish you if you get lazy or make a mistake; we shouldn't have enough armor to play as Rambo and thoughtlessly clear groups of enemies. I enjoy the fact that we have to be aware of how even weaker enemies can move around our cover and flank, or use their own cover and abilities effectively. I don't want to grind through harmless idiots; I play Warframe for that.
That being said, the enemy throws grenades with such accuracy they could probably throw it directly into my hat from 50m away. I can handle difficult enemies so long as they can't directly deposit high explosives onto my forehead.