Yosemite's Visual Design

Yes, you're right, Apple has added more stuff to the Finder, but as you imply when you mention Path Finder, accretion of stuff isn't really progress.

Here are some specific things that I'm thinking about when I say that "the world has changed":

When the Mac came out, the idea was that you'd have a small number of locally stored files from a small number of applications. You'd have some text files you created in your text editor, some image files you created in your image editor, and so on.

Today, though, neither the "few files" assumption, nor the "locally stored" assumption, nor even the "files" assumption holds true.

"Few files": people have a lot of files. They have thousands of images, downloaded mp3s, a decade of documents and letters, possibly hundreds of thousands of emails, electronic bills, applications, and so on.

"Locally stored": files aren't just local anymore. People may have images on Flickr, spreadsheet documents on Google, letters on their Office account, and so on. And files should be accessible from their phones, their tablets, their computers, the web...

"Files": These things aren't even necessarily files. From the user's point of view, is an mp3 a file? Should it be shown in file system? How should something like a piece of music exist in something like the Finder? What about a friend on Facebook, or somebody from your email client's address book, would it make sense to show something like that inside the application that appears when you start your computer? If somebody sends you a file via email, would it make sense for your file browser to understand that relationship, and allow you to, say, browse files based on people?

I think all of these changes in how we use computers warrant a rethinking of how we should interact with our data.