As mad as I am at Microsoft for turning this feature off, the URL specification, RFC1738, states:
"An HTTP URL takes the form:
[url]http://[/url]<host>:<port>/<path>?<searchpart>
where <host> and <port> are as described in Section 3.1. If :<port> is omitted, the port defaults to 80. No user name or password is allowed."
So, username and password were convenient, but non-compliant features.
rfc 1738