Registration makes my site a little smarter and friendlier, and hopefully easier to use.
I rarely bother to comment on sites that require a password, and I dislike required registrations, so C4TF will allow anyone to post comments (at least until spam gets out of control). However, registered guests will soon have optional email notifications for things like new comments.
Security note: Unlike many sites, C4TF does not include your email in page source, accessible to spammers. Email links generate an email to you without the sender seeing your address. You can then choose to reply if you wish.