Not much point in blaming a programme that has been around for about as long as HTML. If you want to blame someone for the worms have a dig at two things:

1. The people that make the worms.
2. The people who refuse to use AV software.

In some misguided belief that those who don't use AV software say "It's okay, I know what I am doing, I've never used AV software and I've never been nailed by ANY virii", I can only utters the words "How would you know this?". AV software, by it's nature, cannot stop new virii on day one. But on day two or three it can surely make a very big difference.

Then there is the authors of trojans. They don't do it because every man and his dog uses M$ Outlook. They do it because if Outlook wasn't there then there'd be another welcome mat for them.

Blaming Micro$oft is just a cop-out.