I guess Savage did this just for cosmetics, since some people don't like the nut.
There will eventually come a time that I have the $$$ and the skills to need a gunsmith to put together a really great rifle -- but the lowly Savage action and nut have so far allowed me to learn how to headspace for 6PPC, get experience with neck turning, and a whole host of other issues on a low $ budget.
The smooth nut would eventually be history, on any I owned, as I'd rather have something that one can clearly get a purchase on!
I just wish Savage built all the actions on the same shank size!