If a player is dying enough that the party literally can't clear the fight due to hitting the enrage, then sure, kick them. But not having that player dying a lot isn't an excuse for the other players to try less. The DPS should be playing as efficiently as possible regardless of whether one of their brethren is slowing down the DPS. Likewise, the tanks should be playing to their maximum potential. So there's not really an "extra load". Everyone should be performing to the best of their ability at all times.
There's nothing wrong with booting a player if it's genuinely impossible to clear because of them. But booting the player just to speed up runs or to avoid potential wipes caused by healer-preventable circumstances is something that I can't support.
Well, it's not a very tactful way of putting it, but I am actually saying that, more or less. That's not to say healers must always carry bad players. If you want to kick the bad players, then that's your deal, even if I disagree with it. But a healer that only knows how to play in a party that makes very few mistakes is a bad healer, in my opinion. Not because they are mechanically bad, but because their experience is isolated. If these sorts of healers are faced with sudden, high-pressure disaster situations, they crumble under the pressure; they don't know how to handle it. I've seen it happen many times. That healer may be the best in the world at maximizing DPS potential while dealing with the minimum raid damage. But as soon as crap hits the fan, they fall apart because they consciously avoid playing in parties where crap hits the fan.
It's a two-way street though. A healer who does nothing but practice dealing with disaster scenarios while never bothering to learn how to maximize DPS and efficiently handle minimum raid damage also has isolated experience.
I don't claim to be a flawless healer. Personally, I have more experience dealing with disaster scenarios. I don't completely isolate myself, though. I actively try to maximize my DPS potential and play in farm parties occasionally. But I doubt I'm as good at efficiency as the healers who focus on that sort of thing all the time.