the other useful technical innovations that get introduced. All it would take is running some bots for a while to switch to the better system, not a big cost for a large wiki like Commons with plenty of bot operators.
I'd like for you to be right. But switching from the present category system to atomic categories is not as straight forward as having a few bots run over all existing cats.
It will require an enormous amount of work. And so far I have not met willingness to change anything. Greg has shown a long time ago that fast category intersection is doable, but the echo has been pretty much zip, nada.
Just note that simply replacing a category with all of it super categories is a dead end. You wouldn't believe the twists and turns in the category tree. Amusing example have been posted on this list already.
So, yeah, sorry for my tone. I've pretty much kept my cool for the last N incarnations of this debate, but after repeating all the arguments for atomic cats and intersections and seeing zero improvement I'm getting a little frustrated. Call it "empiric evidence" rather than "assuming people to be naive" ;-)