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.