SONY SCREWED UP WITH its rights removal to protect its profit margins philosophy and there is no way the use of rootkits can be justified.
If you look at the Sony rootkit, it does several things. It strips you of your rights, it potentially causes your computer harm, it breaks your computer if you remove it, and eats your CPU time. All of these things are bad, no question there. It also does the end user no good in any way, shape or form, not even by the most demented stretch of the imagination. It only hurts those who spent money to buy it.
Say you want to remove the Sony stuff. According to no less a source than The Washington Post, the bare minimum you have to do to remove the rootkitted DRM infection is give up your privacy. If you go to the Sony page, here, you have to give Sony your email at the very least, and according to the WP story, Sony then grills you about your reasons for not liking being rootkitted.