Sigh. There are some concepts that were learned from WoW, certainly, but you're only digging yourself deeper with flawed arguments.
Then counter them, your post is vary vague.
Don't try to make an argument that something is borrowed from another game that was
A) already present in the game
B) the borrowing was in reverse
C) is a standard game design element common to games for a decade or more
etc.
I'll try to stick to a narrow focus.
The standard for death, as set by D&D was the loss of a level.
Everquest copied that flawed bit of design.
WoW broke the mold and improved the design.
4E is influenced by WoW and copied that part of WoW's design.
That is to say, I would suggest that you cease trying to make any WoW to D&D analogies until you actually have researched each point you're trying to make. You might be surprised.
You mean like listening to the designers talk about being influenced by WoW?
3E + MMO design + Minitures design = 4E
Yes there are original elements but the majority of what makes 4E different from 3E is based on lessons learned from MMOs. I focus on WoW because it's the most influential.
The Minitures design is also a factor. In minitures play it's essential to limit options, and limit conditions.
Disarmed isn't a condition that works in a minitures game.
Anyways I've taken us off topic.
The basic answer to take any action in combat you need a power. And there is no universal disarm power. There is a level 17 fighter power.
The reason way is a ten page flame fest, so I'll leave it at that.