I was on your side of the fence for a long time but comments from Snow did get me thinking, why is it fair that sidelining healers in speed runs not for the sake of a challenge because it was not exactly harder the group made a bunch mistakes and had multiple deaths and still had a decent time in terms of speed killing with mistakes and deaths mind you. That is really weird design when you think about it. It is certainly getting the point that what is enjoyable for us, may not be best for the overall game.
I would not like it if my ENTIRE preferred ROLE was sidelined even in small subset because it is legit quicker to cut me out EVEN with MISTAKES. I would be kind of salty. Even if they brought the healer damage up even if it matched tanks in practice, it probably would still be a net gain to not take a healer cause their update would not be as high as tanks if tanks mit and sustain was still enough to meet the healing requirements in conjunction with others sustain.
As stated it really did not seem like it was a challenge per-se because it was cleared with deaths and mistakes but was still a fast clear. Sure healers are needed for majority of groups that is fine, but even so when the exclusion of an entire role proves to be quicker than some standard comps. At that point you got a design problem that is being created by a lack of something or something just being too strong, or both.