-> "and in fact in the first file that you attached the surface is poorly formed in many areas, such as this sudden bunching here"

Yes, something destroyed my holdline as you can see, don't know exactly why.



On some parts it worked fine:



I could imagine for some automotive or package designs it could be useful to keep an exact form projected on a surface (in this case below an ellipse) witch defines the edge where the rounding should begin.
Or you have a nice fading between different sizes of a fillet. Don't really know if it is useful for industrial designs (I'm an architect), but sometimes when I see a form I think that way. :-)
Maybe someone else can give some hints where it could be an advantage to work with. I think its very comfortable to place different radiuses on an edge based on a form.