I use YouTube on Xbox all the time. I also use Hulu and Groove on Xbox as well. I'd use Facebook as the web browser experience on Xbox sucks. Apps can provide a vastly superior experience in some cases, especially where repeated logins are an issue. What I mean by that is apps will save the login info and auto log me in, whereas the web browser will not.
I would like apps for my computer for Live Tiles. A live tile that shows the weather forecast, your balance on starbucks, or when your Uber is expected to arrive or to Shazam the song in the caf? while I'm typing away.
I don't need an app on my PC but I see the Live Tiles as a reason I won't have to open an app ever again. The information comes to me. Android uses Widgets for that, Apple has their 3D Touch, Microsoft has Live Tiles that are leagues ahead of both of those other implementations. The sooner people realize that is the future, the sooner devs get on board.
Speaking of which, developers not jumping on it doesn't mean it isn't the best solution. Car manufacturers didn't start making hybrids and electric vehicles en masse until the Toyota Prius started selling like hotcakes. They are happy to keep selling you the same old thing, whether its the best option for you or not, until you finally stop giving them money for it.
What is the truly innovative thing that iPhone and Android phones have brought to the table in the last few years? They are still dumb launching boards for throwaway apps with more memory and ever faster processors. That's it. They haven't made anyone more productive on their own. Sure they have all these apps, but why do people keep shelling out more and more money each year for these devices without any real innovation in return?