Firefox: Why?

Someone explain to me, when I'm using Blogger in Firefox and I go to add an image, I get this:

Just look for a minute

When I go to add images in the Chrome browser, I get the correct dialogue box, looks like this:

See how there's a button to "choose files" so I can tell the dialogue what to upload to my blog?  Don't you think that would work much better.

Seriously. Someone explain why Firefox started to fail. It used to work fine. (For those of you who are real nerds, it was in both Firefox 3.* and Firefox 4, with and without some Greasemonkey scripts running on that page.)