All good points Michael.

Perhaps there's a middle ground.

Here's an idea:

1. Currently, beginner and advanced users have trouble filleting, especially a large fillet after a model already has a small fillet.

2. There is a large requirement on many (but not 3D printed) models to have some sort of small chamfer/fillet on all edges. Let's call this auto-filleting.

3. Perhaps there can be a way to automate this process in a way which is simple. Set an auto-fillet property for a NURBS solid object (doesn't work on non-solids). Set the auto-fillet/chamfer radius to a number which the current NURBS object can handle.

4. As one starts modifying the solid, the auto-fillet can continue to be added at the end of the editing process. If the fillet is programatically impossible, then it uses a smaller number and tries again. Perhaps this runs in it's own thread.

5. Perhaps one can override the auto-fillet on a case-by-case, edge-by-edge basis, with the understanding it may revert to a smaller number if further edits create an impossible to fillet model.

6. Allow one to "BAKE" the object at some point and no further auto-filleting is possible.

Something like this would make it easier to model because you would know quickly whether or not you wrecked the opportunity to add a 'final' fillet. And furthermore, it would also pop a red flag (no auto-filleting possible!) when something you did created surfaces from a solid object.

Just my 2 cents...