It's tough for those of us who are computer / security savvy to judge what the average user does. I can agree with that 95% of uses have experienced some sort of virus or other invasive software. That doesn't mean that these users have CC problems because of them. Most of this malicious software is adware or info tracking software. I see this sort of thing on family & friends' computers often (the XYZ toolbar, which earns me points and also tracks everything I do online, to be sold to various interested companies).
The problems with this thread have been covered pretty well already. It's a homebrew forum - there will always be positive correlation with shopping at MW (until this thread drives business away from them and toward a possibly less secure site). It's anecdotal, not evidence. A crowd can very easily draw the wrong conclusion together.
On the other hand, it is not common for a relatively small group of people to have so many CC issues within the same timespan (unless it's a group very free with information and/or not entirely bright - but I certainly hope we don't tweet our own CC numbers for fun).
The CC tokening system MW uses is very secure. I wouldn't normally suspect that to be a problem - but since I know very little about their particular implementation, of course it's possible. If MW's servers were hacked, it could be a man-in-the-middle attack, diverting CC info away from the site; I assume this would have been looked at by MW during their investigation. As others have said, it could also be any of the other sites in-between, including the consumers themselves.
Unfortunately, there's not much we can do *as* consumers. As mentioned... (1) Use PayPal (I always do when I can... and have never had security problems). (2) Use temporary CC numbers if your bank offers them. (3) Do not save card information, regardless of system security. (4) Never use credit cards on any small website (not just MW) without a secure 3rd party you trust (like PayPal). ~~ Following these general rules has kept my cards as safe as they can be... and that's the best I can do. There's still the possibilty my card could be stolen at any convenience store.
The only thing that isn't rational (but could certainly be caused by this thread) is to avoid business with MW. You're no safer elsewhere and there's not much proof that MW has a problem...