Well, it isn't really, at least not any more. The original Windows 95 version of the Add/Remove Programs control panel did limit product names to 63 characters. (If you had a longer name, it didn't show up at all because the call to
RegQueryValueEx failed with
ERROR_MORE_DATA.) This limit was raised to around 259 characters starting with Windows 2000, the version that introduced the fancy list with icons and sizes. However, ICE rule 16 still checks against the old limitation because it doesn't know whether or not your program was designed to run on versions of Windows prior to Windows 2000.
If your program doesn't install on those older versions of Windows, then you can disregard the 63-character limit; the new limit is approximately 259 characters.