Sensible usecase for restricting special characters in passwords?
Summary of comments, not to take credit.

Answer so far is: cryptographically no. But it's practical for usability.


Restricting control characters is useful for different interfaces/input methods.
Restricting non-ASCII characters is useful for avoiding bugs with different encodings.
Restricting characters that are not on every keyboard adds to the user-friendly experience (preventing the user from locking themselves out on a different device).
Restricting characters that are in different locations on different keyboards prevents 'habit-mistakes' on different keyboards.
When a password is easier to remember it's less likely to be written down (in theory) see: XKCD #936: Short complex password, or long dictionary passphrase?