Shmeppy is run by one person (me) and I have limited time and resources. Every new problem I try to solve for my users is (essentially) another product I need to design, develop, and maintain. In this case, if I made a dice rolling feature, that would be time I’m not spending making Shmeppy’s wet erase product better.
The wet erase mat is the unique part of Shmeppy, the thing you can’t quite get anywhere else. Dice rolling is very easily solved by another product, so the value to users is much less. I’d rather spend my time on the higher value things.
Lastly: the feeling of simplicity and ease-of-use that Shmeppy gives off is not easy to create. Rejecting features that don’t fit perfectly within Shmeppy’s razor sharp focus is mostly how I’ve created that feeling. Every new button/action/feature is another element on the page, another thing a user has to become comfortable with.
If you’re looking for some dice rolling options, check out this doc. There’s a section for dice rollers.