What does it mean to be a "UI for mobile/touchscreen devices"? Mobile devices already have UIs. What is it trying to add to those? It's obviously trying to add something, unless you literally believe the developers that go to work in that office are setting out to make your life worse.
It's certainly trying to add something of value - the problem everyone seems to have is that it's failing at that task pretty badly.
And not in the sense that the developers are incompetent or lack skill - but in the sense that what they think is a better UI experience is very definitely not an opinion shared by others.
This is further aggravated by the fact that many site owners choose to use them.
It's not trying to add anything to the device. It's trying to add a touch interface to websites based on a common (if itself questionable) paradigm. And it's doing it very badly.
