If you keep your computer up to date and don't open fishy files, you can eliminate the need of virus scanners. Pretty much the only things that will infect you are zero day exploits, and those will get past the virus scanner and disable them in any case.
I would disagree, many full suite paid AV's can be redundant in most cases if one keeps all programs and plug ins updated but there is also malware out there that does not depend on Java or flash to insert itself.
Many average users do not understand threats, particularly social engineering types and allow the threat.
I have used MSE and Malwarebytes pro for a long while and both have saved my butt a couple times even though i am a fairly knowledgeable user and do not surf indiscriminately. I advocate a dual approach to web safety.