Not sure what to think about it. Seems awesome at first glance but then the examples are skipping songs and hand waving pokemons. Feels a lot like a solution looking for a problem.
Agreed. If I'm so close to a phone, why would I swipe in the air? I also believe that making those Soli actions requires more muscle energy compared to tapping the screen with one finger.
Because you don't want to extract it from your backpack/purst first? Or you are lying in the dark avoiding turning the backlight on but you also badly want to skip that terrible song you hate...
edit: or you're presenting and using your phone on the podium as a remote without breaking eye contact/physically fiddling with the phone/laptop.