Adobe remove the code and is pointing their fingers at Microsoft and Apple...
Lost two features, Photoshop has. The Adobe Jedi have waved hands and said, "these are not the features you're looking for".
You can conceivably put a Bridge icon on the desktop near where it used to be, and leave a little room outside of the Photoshop application frame where you can see it, or use the File - Browse In Bridge menu item, or Alt-Control-O (or the Mac equivalent if you're on that system).
If you're on Windows, you could consider getting a codec pack that will provide you thumbnail images right in the dialog and Explorer windows. I can recommend the one that I use: The FastPictureViewer Codec Pack.
Apple and Microsoft both decided that they would limit customization and file access in the open and save dialogs in upcoming OS versions. (the open and save dialogs are OS controlled dialogs, not application controlled)
Photoshop went ahead and removed the previews and cleaned up our customization before we were forced to. Other apps will have to do the same soon.