The reason all those other 3D programs use an Autocad interface is because it's a standard, it applies across all the programs, it makes it easier to learn new or different applications. Rhino is very much like Autocad, it's like a friendly version of it. Autocad is beyond deep. Rhino is deep as hell but a lot easier to learn. Amapi has a very unique interface, it's kind of like Bryce and Carrara but it's different, all it's own, it's ingenious, I just can't get use to it.. I do wish Rhino fillet tools were as smart as Amapi's though.