I have just made a 1-line user feedback on how C&D works. To do that I had to register my email address, confirm the email link, set a new password and then log in. I am surprised I went through with it all. I'm sure there are a large number of people who got put off and stop trying to give you the feedbcack, as I would be myself most of the time. I prefer being able to just write the comment and submit. If you have to have user registration, it's better just to use your click-and-drop account details, rather than having to set up a new account.