The accept header value has to be set, it does not default to application/json like the other routes.
I've been thinking o trying to make the default be HTML using the current TT for detailed view. That's why I left it like that. Otherwise people would start using it without setting the Accept header and it would be a breaking change. But you are right the other ones don't require.
*** This bug has been marked as a duplicate of bug 24237 ***