If you are using simple base like this, I don't think the slight detail on the top is inconsistent with a plain casing

Yeah, I think I did that in my last house. I used 1x select pine for all the window and door trim, then 4” regular baseboards all around. The baseboards were thinner than the 3/4” thick pine, so they butted up against it nicely. The edges were not eased, but that’s easy enough to do. I think you need to make sure the baseboards will butt up against your casings nicely and see if the thicknesses work together.

I had shaker doors for interior and they looked great with the new trim.

Is this what you mean?

1x3 casing, 4.25” baseboard

Yea, that is exactly what I had in mind. I think it looks nice. Thank you!