Shame the GPE program never took off. =T
Frankly, because most people don't care specifically about 'stock Android'. I never hear anyone I know that uses Android complain about software bloat, that TouchWiz or Sense lags (I could probably ask 10 random Galaxy or Note users what they think about TouchWiz and I guarantee at least 9 out of 10 response will be 'What's TouchWiz?'). Hell, many people refer to all non iPhone's as 'Droids'. Ask general consumers about Nexus devices and you'll probably get the same quizzical look you got when you asked about TouchWiz.
The dearth of quality hardware running stock Android is a geek or tech nerd's problem. GPE didn't take off because it didn't sell. It didn't sell because they were comparatively expensive (they factor in most consumer's decision) and sold through a single online channel. It's the same reason why the Nexus has never sold in significant quantities. And unless Google really pushes...I mean, put some serious capital behind it...to mimic Apple's vertical strategy, stock Android on the highest quality hardware is probably not coming any time soon.