I have the same problem. According to the thread at http://forums.macrumors.com/showthread.php?t=1656852 , the 32-bit code for Quicktime was dropped as of OS X 10.9, and since iTunes depends on Quicktime for playing media files, iTunes can no longer be launched in 32-bit mode. Mac's first 64-bit operating system, OS X 10.6, was released in 2009. The people who maintain the ogg format, the Xiph foundation, haven't updated their Mac ogg plugin, XiphQT, since earlier that year, which means that it was never designed to support 64-bit applications. The 32-bit mode circumvented this for a time, but Mavericks ruined that.
The only way to get ogg to work on OS X 10.9 would be to download the XiphQT source code from the website and try your hand at coding up and compiling a 64-bit version.