This is perhaps because the Imperial family themselves still lives in the premises. This is why the main area of the Imperial Palace is closed for public, except on two specific day of the year, which is January 2nd for New Year's Greetings event and December 23rd which is the Emperor's Birthday.
The Imperial Hotel itself would be demolished in 1968 to make way for a new, larger hotel. Portions of Wright's Imperial Hotel were saved and rebuilt at The Meiji-mura open-air architecture museum in Inuyama, near Nagoya.
