Because it's already in there, they have to do something to take it out. But that said, I don't know why -- I'm just a user of Firefox. Haven't wanted to switch because of things like this. You get used to the quirks of a product.

I'd be fine with an extension in Firefox, but like the author I use this ALL the time. And I'm not a fan of the Chrome extension. It doesn't even show the feed URL in the address bar.