Do you really want to softfork to add that functionality as a default?
A soft-forked change cannot be mandatory, it will always be opt-in, by definition.
Enhancing Bitcoin privacy is a must, and not for "die-hard" reasons. The privacy of transacting in a form of money affects it's effectiveness in performing the role of being money. The goal is to implement and popularise a form of independent electronic money, and so compromising Bitcoin's money characteristics is obviously anathema to that goal.