I care a lot (see my other answer below). I've - successfully - pushed for Persona with all of my clients, I sell it as "Sure, I'll do Facebook authentication for you. I'll even add Persona auth for free, your Firefox users will love it!". Clients love free features.

I also push for it very hard in open source projects. This is where the change needs to happen. Wiki software such as mediawiki for example is ubiquitous, if it can be automatically configured to present the user with a Persona option a lot of people won't bother disabling it and will see it as a nice bonus.

And unlike OAuth, Persona can be readily available with zero configuration! It doesn't need API keys, that's the beauty of it!