Upscaling to 4K is little more than a gimmick at this point. Any 4K display will automatically scale to it’s native resolution, so this function in a player has limited value. It’s also not likely that a $250 player will do a better job of scaling than a $10,000 display, although anything is possible.
Now if the player actually supported playback of 4K video sources, that would be a different thing. (assuming any such sources existed)
But I’m sure everyone is excited to see their 480 streaming video scaled to 4K.