On-line creativity

I read a lot of fan fiction. Fan fiction based on many different shows, manga, and books. The one thing I notice more than anything is that a creative writer who uses known characters in unusual situations for that character tend to get beat up by their fans.  People seem to develop strong emotional attachments to these beloved characters, a since of ownership. Now if you write something completely your own is it received better? Or do people again develop a strong emotional tie to the characters and feel a need to dictate what can and cannot happen? And is it really a bad that this happens since obviously someone wrote a character that grabs at our emotions so strongly?