If you're gonna be typing on a low-profile board, you want a case that doesn't add that much height to your keyboard. It gives you a bit of extra protection with a small rim around the PCB, as well as a cutout for a relatively large battery (I'm using a 300mah lipo). The subtle 8 degree angle incline makes it slightly easier to reach the top row without increasing the height of the board overall.
The cases are printed through Craftcloud® by All3DP, as they offer significantly cheaper prices for printing than most services and have way more color options than I do. (Not to mention that it's less work for me!)