It is always good to have an emergency button.

Not sure why you would want to say "naw, I'm fine with having fewer options".

Even if I believe that you never needed something to save your life (ps: I don't believe you) it can help lessen damage taken during big damage and thus lessen your healer's strain.

Think about it this way, even if all damage is completely predictable, wouldn't you rather your healers have to heal 7 people rather than 8? Or, in a more single target case, what if you need to soak some big mechanic? Why not just take no damage from it, a la BLM. Would you rather have that option?

This isn't about "git gud" or the ability to get something done or not, this is about options.

And while I think MCH doesn't need one, I certainly won't complain if they get one.