Classic wow was piss easy, anyone could do it IF they had enormous amounts of time to throw at the game. That's why it was so popular.
Now that wow is more like an arcade game with rpg elements, it's less popular.
Gear caps can be overcome by anyone with time to spend (i.e. fire res gear farming, simple patchwerk bosses that just need more number output to beat etc). Skill caps are naturally exclusionary because if you don't naturally have the skills you are SOL on doing current content. A player who hits a gear wall just thinks "ok I go farm some more and come back" but a player who hits the skill cap goes "oh well, lets find a new game."