Except that all of the studies suggest the headphones / earplugs option doesn't help very much. Most of the damage is done because of lack of privacy and noise is a secondary (though still large) effect.

The headphone solution is also insensitive to people with extreme aversions to distracting sounds, such as sufferers of misophonia. In a lot of cases, if you are embedded in an open plan, there is no such thing as "opting out." It's a fixed decision mandated upon you.