I agree with your feelings on the binding-ED programs. I read about Georgetown's and did a double-take because it seemed so unappealing. Who wants to be tied down like that before they know all their options?!
I think it's mostly for people who don't really know what is going on and think it will help them in admissions. Also, I think its for the people who are like "Georgetown has been my dream school since I was 14, I will go there even if I got into Yale."
You would be surprised at how many of these people there are.
I really don't get it at schools with both EA and ED. The only way I could see it helping you is if you might ahve been a yield protect rejection. If schools are really taht concerned about protecting their yield, then just require like 5 optional essays like Penn and Mich do.