Um. Well. Professionally, I have to say you're wrong. I spend many hours dealing with the results of letting people just use machines without protection. I'd love to take you into our computer lab and show you... the people who log in are all CS students, so they ought to know better. They have very limited access to the machine. And after a semester, the machines are still so goobered up all we can do is reformat and start over.
Also, virus scanners do not, usually, detect spyware. That's why one needs both. I'm glad you're lucky so far but it's really not a conspiracy on the part of the spyware cleaners. After all, the ones I use are free. So what would they be getting out of it?
What are the spy and adware writers getting out of it? They're also free.