Yeah, let me go into more detail on the pain points so you can determine if it matters to you or not.
The biggest pain point is if you want to display X number of topics with their respective columns (that exist today on the Categories view).
Do better visualize this, see the below image (where the arrows point to)
Those will be your problem areas. However, you can get around that partially. You could create a new model that returns that data that only your customization would use. It queries SQL and caches and so forth.
If you went that route, any changes by Discourse would likely not damage you too much (unless they move things deep down in Core that deal with how you query Topics, how you Cache results, etc.
You could then create a template/view that has the Groupings hard coded in the design and each section then puts their respective sub-categories and topics however you see fit. Technically you could create a view like latest under each category and limit it to the 10 recent topics (if you wanted).
Where you will run into pain points is if you want to reuse the categorries model that already exists or modify its templates directly. That bit us for a long while with our own theme and we've recently moved away from some of our customizations to get rid of that nightmare.
Anyway, this is more "food for thought" and a better explanation of what I meant by pain points.