The thing the "haters" don't get about sit-stand desks is that it's not about "standing is healthier than sitting". Both are bad if that's all you do. It's meant to get you working in a couple different positions throughout the day. And since it's one button touch (maybe 2) away, people are more likely going to utilize it than it it were, say, a hand crank (which are almost all just seated height adjustment anyway), or having to push in a pin to adjust legs, which isn't always a 1-person job.
The other way to accomplish a similar thing is to get a fixed height desk at the standing height, and then get a stool...but to get an ergonomic task chair style stool, you'll likely be spending the same amount as you would have on an electric table base.
Oh, and treadmill desks aren't for practicing for your upcoming marathon while you're huffing and puffing on a conference call. It's really meant for a leisurely stroll at a mph or two, just to get your blood moving. Nobody is working up a sweat or running out of breath at these things. Besides, they generally aren't someone's primary desk...it's usually one or two that people can grab their laptop and hop over to them to work for a little while; a shared resource.