There is a nice little feedback form on the Universal HD web site. I would encourage others to use it if they have a moment. Of course, be polite and professional in addressing your concerns. If you're happy about some of the changes, it's only fair to mention that as well.
I tried to emphasize that thanks to parental controls being standard on digital receivers, UHD (and their advertisers) don't need to worry about content like they would with channels available in both analog and digital forms.
Other good points have been made in this discussion so far, and Universal should hear each of them, ideally from different people rather than all lumped together. I'm sure it would be better to have a larger number of people file complaints so that they are more likely to accept the fact that they are losing many loyal viewers.
Just click the "Contact Us" link at the bottom of the UniversalHD web site to get to the feedback form.