Making a digital model is easy but making a GOOD digital model is every bit as hard as making a traditional one, or at least, that's what I believe. Ultimately, it's about what the sculptor wants his creation to look like. If there are now professionals who have established themselves for decades with traditional scuplts then a comparison to a starting amateur-with-an-etsy shop is not entirely fair.
There are professionals picking up digital sculpting, some on this forum. Most of the time I think I can notice a difference but that may be just style. Maybe my imagination but mostly too perfect, too smooth, too symmetric to look perfectly natural. But in smaller scales, Mithril for example has gone fully digital (casting from the printed master, not selling stl files) and the style matches the older models amazingly well. Then the warhammer stuff. I think that style is very suitable for digital modelling. Most of the available stl's are in that style anyway.
Business-wise, I don't believe that selling stl's will ever be big. If we have concerns about recasts then just think how much easier it is to copy a file ...
personal note: started on crafting a wagon from scratch. I wish I had a nice resin printer (or even a not so nice one). CADding a round wheel must be so much easier than trying to spoke bits of carton with match sticks ...