The IE guys are going to have to fix any problems in how it plays nice with Windows anyway, and if the development process is so broken that they can't even keep O/S-breaking regressions out of the builds, there's a problem.
The problem is that IE is tightly coupled with several other Windows components. This means it can break many other apps which can depend on it, or also can break itself if it depends on something which is not available.
For example, when IE7 came out people were extracting the installer package and installing the individual components inside to bypass the WGA check. If they didn't install the XMLLite component before the IE application installation, it would break several applications including Explorer. It could be fixed if the user booted to Safe Mode and installed the XMLLite package or DLL afterwards, but many users probably didn't know that.
This is exactly the kind of thing Microsoft wants to avoid...people breaking the system because they don't have the proper dependencies installed or some other factor with their configuration. It's much easier to roll it all together into a release canidate where they can be sure it includes everything it needs.
Hey, I'll give Ronald Reagan credit for being a part of it, but Gorbachev is the important one here. Gorbachev had to pull out of Afghanistan, he had to let the Eastern Bloc Warsaw Pact nations determine how to handle their internal affairs. All of this was guaranteed to greatly reduce his own personal influence, and had a good chance (As it turns out, great chance) of greatly reducing the influence of communism in the world. Seeing as how Soviet Dogma suggested that the communist revolution needed to spread across the globe in order to succeed, he was basically blowing up his country in exchange for peace. On the other hand, America pretty much carried on as before.
In related news, USAF Gen. Kevin Chilton, head of the US Strategic Command, opined today that the US needs *more* nuclear weapons.
To do two things at once is to do neither. -- Publilius Syrus