Was just about to ask the same question. I can't come up with a single Android app I'd like to run on desktop. Is it just an app development thing?
It's a total pain for me to have to always open my phone and use the tiny keyboard to carry out some trivial task.
Even stuff like TextPlus that lacks desktop clients. I can think of quite a few apps I'd immediately grab.
I could see myself using this if I ever bought a windows tablet.
For example, if you like comic books, the touch friendly comic readers on windows are pretty bad. Also the biggest comic store, Comixology from Amazon, is not available in a windows app version.
So that is one use case! They even tend to support tablet layouts.