That said that for the X Box One X which it still doesn't make any sense, since the game and the UI don't run at the same time, it's not like a PC that has borderless window mode where you desktop is active while the game is running in full screen
but we're talking about the series x, they could easily made the GUI 4k
I'm guessing they took the better safe than sorry approach. I def get what you're saying though...on paper they have more than enough resources for it.
Engadget is now a part of Verizon Media
..."but every bit of extra RAM doesn't hurt, as Ybarra explained that even when games don't use the extra RAM directly (read: unoptimized existing Xbox One games), it will be available for caching to speed things up"....