I disagree? Waaagh energy isn't made up of the Winds, and there's no indication that it feels the need to flow back the Aethyr like they do. The Waystone Network is based upon the Geomantic Web, which itself is designed to work with the energies of the Old Ones - i.e. the Winds. I've never seen or heard any indication that prolonged exposure to Waaagh energies does anything to anything that isn't a Greenskin (or Mathilde that one time), unlike Dhar which famously does, so there's been no need to try and drain it.
If you have any evidence otherwise I'd love to hear it. If we could create mechanisms that drained Waaagh out of the area that'd be rad as hell, even if they were big and stationary defensive works for Karaks and the like, to defend against sieges with. I'm just not sure it's actually possible, you know?