Yeah, 4.0 out of 10.0 is more like it, for the half-advanced user anyways.
You see, the primary infection vector on any machine is, of course, the user. The user just doesn't get it- they are insecure (in both applications of the word), and so they need idiot protection.
So perhaps it's a good thing that IE9 is at least twice as secure as the users.
Besides- those users will download every browser they see out there (here's looking at you, Safari) just because.
You see, people like us are smart enough that these "ratings" become irrelevant. Users that use different browsers and don't believe we're the millionth visitor to this page.
For example, Firefox (3.6 and beyond), with Adblock Plus (no flash ads to tell us we've won something) and NoScript (to ensure that, even in dangerous sites, that things aren't going to be stealth-downloaded), will be faster than any other browser out there. Why? Because loading ads and scripts always slows the browser down- no matter which one it is.
(It's interesting to note that this little fact is not in benchmark runs.)
Can and do we totally ignore safety and security? Of course not. We just don't need to do as much since those best practices are already in use and ingrained in our memories.
So while I don't agree with arbitrary, semi-fake benchmarks from the companies that make the software, the reality isn't all bad.