She doesn't like to face any press that she can't control. It would be disastrous for her to have to answer questions about her corruption and dishonesty.
She has a lot to answer for and she doesn't want to take a chance of a reporter wandering off the Libtard reservation and asking her questions that would reveal her lies, incompetency and corruption.
Besides, she is a dullard and not very good thinking on her feet if the discussion goes off the script her handlers prepared for her. In addition in a non scripted event she always comes across as a hateful ugly bitch. People don't like the real Crooked Hillary when they see her.