Here's the response I got from UAL Customer Relations:

Dear Premier Monkey,

Thank you for contacting us. Your comments about making reservations
and receiving a ticket while redeeming a paper certificate are
appreciated. I know that when United fails to deliver the online
service you anticipate you doubt our desire to be an airline you can
count on. You may be assured that we are continually working to enhance
united.com and improve the online product offering. Our web developers
are working toward electronic entitlement, which will finally replace
all paper certificates. In the interim, while there is a fee to issue
your ticket, we'll try to make ticketing with a paper certificate as
easy as possible. That is, you may exchange your paper certificate by
mailing it to our reservations center. Your ticket will then be issued
according to the terms and conditions of the certificate. Please ask
our reservations specialist for details.

We're also working on other web site improvements. In the next several
months we are going to be launching the ability to search by number of
connections, flexible date shopping, the ability to search for alternate
nearby airports, and improvements to schedule-based shopping. For 2005
we are working on additional fare shopping and site enhancements. Your
good comments will be given to our web design group to help us focus on
specific areas important to your united.com experience. We appreciate
this opportunity to respond and look forward to serving you.

Regards,

Rich
United Airlines Customer Relations