Yeah, but how difficult is it to make a distance field with the same versatility as a spline which lets you drag its surface, explicitly add seams of lower continuity (which are important out past the second derivative for reflections), shell a surface to uniform thickness, etc?
Blending shapes is neat trick but the market cares most about fundamental operations and it seems to me that the fundamentals are harder to implement with CSG.
Yes, it's definitely a tradeoff. I wouldn't think distance field modeling will ever be mainstream in design for manufacturing, just like CSG won't be. They are mainly useful in direct visualization. There may be lost of niches such as content creation for gaming etc where other representations can be useful.
Blending shapes is neat trick but the market cares most about fundamental operations and it seems to me that the fundamentals are harder to implement with CSG.