That feeling of anxiety when looking over software should be taken as a cue to get better at it, not a feeling to be processed as such. Because it goes away as mastery goes up. Pretty soon all that whitespace becomes anxiety-inducing in and of itself
I think you're making condescending assumptions in order to explain away my different preferences, and I don't appreciate that. The feeling I'm experiencing is not anxiety at not knowing how to use the software or read the information presented, I am very comfortably a power user of basically every piece of software I use regularly. It's simply the fact that high levels of visual noise are more difficult to process than when information is clearly separated out and grouped and given enough visual space to be processed independently. Dense interfaces are just less visually restful. This is why I actually tend to prefer pieces of software with little interface at all, just keybindings, like my config of emacs. And I see no reason why being a power user would inherently make white space anxiety inducing, since there is no sensible psychological mechanism for the two to be connected in that direction, unlike the sensible psychological and vision processing connection between dense cluttered interfaces and a feeling of visual clutter.
Furthermore, my feelings in this matter extend far beyond user interfaces: not only do I prefer clean user interfaces with generous use of negative space, I prefer that in my books, and the walls of my house, and the organization of my room. If my wall was covered in posters and sticky notes, instead of a nice clean beige with one or two posters, that would make me feel anxious as well, and it isn't because I don't know how to read a post-it.
