There are things where you can't do without preemptive multitasking. I remember that under Windows 3.1, I couldn't download a file over zmodem at 2400 baud while doing anything else, whether the terminal application was DOS or Win16. With the same DOS app, on the same computer, under OS/2, I could do pretty much as I liked while downloading.

Cooperative multitasking has gotten a lot better these days, though, in the form of coroutines and async io.

I suppose we should do away with page tables and virtual memory then as well.

Maybe you weren't around to witness the instability of cooperative multitasking under both classic MacOS and Windows 3.1/95, or you've forgotten.