I completely agree, Tim.
The privacy issues are the biggest frustration I have with ancestry.com. It drives me nuts that people can take my information, but aren't willing to share. I was really annoyed when people were taking photos where I was the photographer, I could see that we are cousins, I could see that they were constantly on ancestry.com, but they would not answer my e-mail when I offered to collaborate. Of course, this problem on compounded for me with DNA testing, as your post mentions.
All that does is create tons of crappy trees on ancestry.com, with limited mechanisms for correction. I much prefer Wikitree's one person one profile philosophy.