Have you checked the "CDs/DVDs" section of System Preferences? There, you should be able to tell it what to do with blank CDs. "Open Finder" is what you want. It sounds to me like it somehow got set to "Ignore" (which is what I use, and gives me the same behavior you describe).
Incidentally, you should still be able to burn discs from the Finder by using Burn Folders. It works a lot like what you're used to, but you don't need to have a disc in there to make a Burn Folder, and it doesn't require a full disc's-worth of free space on your HD.