The UI is not clumsy because you cannot find where to download 4k assets, because here is NO such option on the Xbox One X to do so. You call the UI clumsy, but it is more that you don't understand how the updates/4k assets work.
On the Xbox One X there is no such "download 4k assets". The system itself is a 4k device, so when you buy a game at retail or digital, it will download the 4k assets or the patch that it needs on it's own. You might be confused because prior to the launch of the Xbox One X and even currently for owners of the OG X1 or XS there "is" the option. This allows people to pre-download the stuff before moving onto the Xbox One X. You then network transfer or have all the stuff on an external HDD and when you get the "X" you just plug and play. If you own a Xbox One X and have games that "Already" have an update or assets the system will download them when you attempt to install or launch the game.
Sorry for jumping on you, my intention is not to slam you. It just get's irritating when people call the UI or features bad when it all is just the end user not knowing/understanding. Kind of like a guy a few pages back going completely off on MS for designing the "stupid" UI and the "stupid" Audio settings. He was bitching that MS was too stupid to allow you to have 5.1 or 7.1 uncompressed audio for games only and another source for watching Movies. That MS was too dump to give users the option to allow users to choose both. That it was dump that he had to change it to 7.1 uncompressed for games and when he wanted to watch a movie he had to change it to bitstream 7.1. Then another poster puts up the answer that there is such a thing and that you can have 7.1 uncompressed for games and then tell the system that for movies to allow the receiver to decode the audio for movies, so the receiver could use whatever is encoded on the movie and adjust the audio without having to change setting between games and moves. It is something that has existed for a while, but since that person could not figure it out, he basically called the UI stupid and the Devs idiots for not allowing something that in fact was allowed. I guess it is easier to call something/or a team/company being stupid or clumsy instead of asking/researching if things are possible if they don't understand before calling it clumsy or telling the team that made the UI/Audio settings "stupid".