I'll argue that 99% of the time I have the hope of watching somebody that I think might pull off a meme spec play one... its just crushed under the failure of the spec and not skill... "this dude is gonna bring it with enhance/ret... *fart*"
Sure arena punishes the meme specs less than an open BG... but, you are only gonna get so far. Windshear does not come back faster because you have more skill... there are just limitations to what you can do at 20 versus something like end game where there are FAR more things to do and choices to make per second.
That being said, I'll 100% stipulate that arena at 20 has its own learning curve and I stipulate that "some people suck".
I agree that you can't push something beyond what it's capable of - but I think rarely is anyone ever pressured to push something that hard in BGs. Individual skill is a factor in winning a BG - but it's much more subdued compared to average team skill, how tryhard people are willing to be to focus on objectives, comp dynamics (as you say, skill is pretty meaningless when it's, as an example, 6 hunters + 4 healers vs. 1 healer, 9 non-hunters), etc.
In arena, you still have comp dynamics - but really this just means "Hunters", since counter comping is very, very, very far from being the most outcome determinative thing in skirmishes right now. You generally have to have a pretty elite playing field before counter comping matters.
I think a big part of it for me is that most hunters are actually not very good at the game. Shocker, I know. In arena, where they can't rely on smashing their face into the middle of a giant teamfight and wiping your group of levelers faster than you wipe theirs, it's a lot easier to outplay their lack of game mechanics.
Your skill can have much more impact. You have more LoS potential and fewer players throwing themselves at you. It's much easier to simply throw frost shocks at the MM casting Aimed Shot, then line at the last second, repeat. For Survival, you can Unleash Shield their engage and try to beat them at a range while they're slowed. Do they still do ungodly amounts of ranged damage? Sure. But it's almost - *almost* - at a point where most hybrids can 1v1 them in a ranged fight.
tl;dr, skill is a bigger part of the "do I win" pie chart in arenas, imo.