We have a whole valley full of people talking UNIX versus MS-DOS. What do you need any of that for? Just throw it all out; get rid of all that nonsense. Maybe you need it for computer scientists, but for people who want to get something done, no. Do you need an operating system? No.
The system should treat all user input as sacred.
I've moved on, grown and learned in the years since then, and am designing interfaces that make the Mac's GUI feel as clumsy to use as the Mac made the old DOS-based systems feel primitive.
Icons, windows, mice, big operating systems, huge programs, integrated packages.. I would like to remind the world that just because two things are on the same menu doesn't mean they taste good together.