I think it's courtesy to play the best you can when you are paired with random people. I don't care what you do with your friends and stuff. But when you are with random people maybe, and only maybe you should stop focusing on yourself and think about the others. And if you can't do that, maybe play only with your friends or play an offline game. I can't believe we are discussing if it is good not trying your best when you are paired with random people as a healer.
In the end of the day you can play however you want, but maybe instead of thinking to much about me me me me me me me me. You should think about the others. I'm healer and I will play as the best I can, and it won't bother me at all this discussion since I'm the one playing the healer role, but well... It's disappointing seeing all of you thinking that just doing the minimum required it's good enough when other people might be (or might be not, who knows) doing their best.