Well one reason why adoption matters is network effects. Increased Linux popularity, means that more developers will develop for Linux. At a broader level it means that the ideology and principles of the Linux community, like software freedom and privacy, can produce quality results and products for the masses. That brings more power for the Linux community, and more adoption of their principles.
On the flipside, if the base Linux experience is mediocre, then nobody will bother developing apps and extensions for it.
If you are completely happy with Linux the way it is now, then that adoption probably doesn't mean a lot. But I personally think there's a ton more that can be done in the Linux and privacy world