If it's opt-in and opt-out, then the skill won't always activate when the healer uses it, thereby throwing the healer off and wasting their time to judge the situation and try to pull you to safety. Human error is normal - all players make it, whether by being DPS, tank, or healer. Trying to remove a healer's utility because you don't like it is because they have the possibility of griefing you is comparable to the healer saying "I don't want you to greed for DPS because you have the possibility of taking damage and making my job harder, thereby griefing me".
In that case, you might as well just sign an opt-out raise of shame if you ever happen to die.