Tri-spokes. A thing of the past?

Tesseract

Sorry to bring up yet another "which wheels are best" discussion, but...

Everything I've read on aerodynamics indicates the trispokes are probably better (less spokes, aerodynamic spokes, deep rims etc), however you see less and less people using them.

Is this because there's only really one big Manufacturer selling them?
Is it down to the advertising hype from Zipp etc.?
Is it because they tend to be heavier?
Or are the new deep rim wheels truly better?

Discuss...