Only conspiracy theorists will believe the scenario that all remailer operators are turncoats. There's a fix for that. This is done by encrypting the message with the public key of the final remailer on the chain. And so on, envelopes within envelopes, until the message's privacy is virtually assured. There are currently about twenty remailers operating, but they come and go, especially since many network providers have problems accommodating them.
Anonymity is scary stuff.
Even in their experimental infancy, remailers have had an effect on Net culture. On one hand, there's been an outburst of harassing or simply idiotic flames that have no return headers. On the other hand, there's now a way for victims of sexual crimes or whistle-blowers to send mail and messages with the assurance of privacy. At this point, however, probably the most important role that remailers play is to launch a necessary dialogue on the issue of anonymity in a digital society. For more information on remailers, including a current list, you can download information from the ftp archive at soda.berkeley.edu.