There's lots of 'Do we need Kaspersky' type questions in here already. The more pertinent question is whether AV is actually effective, or if stronger countermeasures like application whitelisting are needed?
You would need a document whitelist since many programs can be hijacked using buffer overflow attacks or outright support execution of arbritrary scripts.
I'll also point out that defending against buffer overflows which are considered vulnerabilities is a far saner boundary than a blacklist of files which grows infinitely.
Or we could, you know, just stop using Microsoft Office and Adobe products which are a huge, if not the biggest culprit of that kind of crazy behaviour.