UI is probably optimized for console and TV 4K display.
I find generally that the higher the resolution, the smaller the UI is in comparison to the screen size. In this game the default UI for 1440p is smaller than it was on my previous 1080p monitor, which was smaller than on my previous 720p laptop. Even the computer's homescreen icons are smaller physically, the higher the resolution. In Marketplace the UI doesn't seem to scale down, so when you're on a larger screen the UI is physically bigger. On my brother's 4K TV the pack images will be even bigger than my phone's physical size.
