They should be factored for this reason (I don't agree with going test optional), but the weight at which they are factored is not as high as many people believe.
Much of what plagues the U.S. college admissions process is the idea that these are prizes to be won, that the accomplishment is in the receiving the offer (whether you have any intention to enroll or not). I am talking with my junior year son today about what he asked me to do yesterday. He got mailings from Princeton and Columbia and wanted me to mail in his response form to each school. I respected his wish, but I am going to ask him what is important to him, what does he know about each school, and how those two things connect.
I know I am going to get, "Well, it's Princeton!" Unfortunately, that isn't enough, but that is where it begins and ends for nearly every kid (and ESPECIALLY his/her parents) out there.