1)Speed running requires the tank to know when to pop which CDs, when to save bigger ones for certain pulls, and shield swiping properly makes some huge pulls possible. Probably not much so anymore with gear, but it's still a skill-dependent trait.
2)I agree that speedrunning is harder to heal than to tank, but that does not diminish that it requires more skill as a player to tank a speedrun than single pulls. "Healers should not have to work so hard" is, frankly, irrelevant to if it requires more skill or not.
3)Dungeon content is different than coil. speedrunning requires a different set of skill than coil. Being good in coil does not mean you are good at speedrunning. Being good at speedrunning does not mean you are good in coil. Different content is different. I've never made any argument that might suggest otherwise.
In dungeon content, it requires more skill to speedrun than to do single pulls. It is not reckless if you do it right. It is not the intended way to tackle the content, but it is definetly not reckless unless the tank overpulls (another tank skill dependent trait).
Everything in this game is gear dependent. Speedruns require both gear and skill. Both help with making a speedrun faster and more successful. You cannot attempt a speedrun unless you have gear. However, I've healed an ilvl 90 tank through the new dungeons and they speedpulled as much as possible. A less skilled tank who doesn't know when to use which cooldowns could not pull that off.
It just seems like you're grasping at straws in order to sidestep admitting that speedruns take more individual skill than single pulls. Which is silly, because if I ask any random person not involved in this discussion, they would agree.
I apologize for mixing you up as someone who does not like speedrunning. It seems we disagree on which is more skill-intensive; not on if speedrunning should be done or not. ^^