The issue is that these tools are used in day in and day out by a specific audience that is willing to make the investment to surpass the bad parts of the UX. It's not like a 3D artist can choose to skip using a 3d package - and in many cases the choice which one will also be dictated by external factors. Once the initial hurdles are surpassed, the UX of the tools does work well for that flow. It has to, because that's the customer base.
Basically, these tools can afford to suck in the basic UX because they can't really "bounce" users there.
I do believe that by that metric Blender UI is not that bad.