It's from Joel Spolsky in that post linked by the grandparent, from 2006. And that's exactly what I'm saying - it was one honking great idea. Microsoft saw how central the web is becoming, and integrated it into the OS
As for legality, I'm not a lawyer and definitely not an antitrust one, but as I see it, an OS is almost by definition an amorphous collection of tools that users need to make proper use of their computer and nowadays I can't imagine an OS that doesn't come with a browser, so would argue that they were absolutely right in integrating it. If anything, I see much more merit in suing them for abusing their OS monopoly to go into the solitaire gaming space.
You're looking at it from the modern perspective. What Microsoft did was use their monopoly power to destroy a potential competitor -- the first step of the "EEE" trifecta.
I'm not a fan of Microsoft, but I don't think that they, or anyone, should be disallowed to Embrace new technologies. There has to be a better approach to antitrust.
As for legality, I'm not a lawyer and definitely not an antitrust one, but as I see it, an OS is almost by definition an amorphous collection of tools that users need to make proper use of their computer and nowadays I can't imagine an OS that doesn't come with a browser, so would argue that they were absolutely right in integrating it. If anything, I see much more merit in suing them for abusing their OS monopoly to go into the solitaire gaming space.