I can see any variety in battle is not desired by the rigid playerbase. I guess no one else gets bored doing the same melee swing/block fest over and over. Most players would also like to play the same map over and over if they could that they have memorized so they can max out their k/d r. Boring. Is an occasional very small chance at KO really going to disrupt your game that much? Apparently. Ah well, no new ideas to make the game more interesting are wanted. I will remember so as to not suggest any anymore.
It's not so much that we don't want new ideas, it is that for many players, being KOed at the start of a 5 minute round after getting hit once will simply make the game far less fun and as you said, much more
Boring.
Getting headshot or couched right off the bat generally happens because you were not on your A game and not paying attention to your surroundings, and are in most cases avoidable. Having this feature, however small a chance to occur it may have, would make you have a really bad time. Say you charge into battle, you've weaved in and out of archer fire and cavalry the whole way up to the enemy lines, still have all your health, you're ready to get into the fray... then you get bopped on the back of the head and are down in one hit. Time to wait another 5 minutes to spawn again...