You got the point but it would be better to have their own app but as said it wont really be that simple and it would takes time.
You've just said about mobile version which is already available on most gambling sites nowadays and yes, its quite hassle to have that
entire full webpage scrolling and zooming in and out. Mintdice team is surely making up some progress on making this site way more better.
Mobile web is coming first, and then development from there can progress into an app relatively easily. So that's definitely possible, but that would be a while longer. The mobile web design that is coming out should be quite good though.