Candidly, I think the easiest way to have a simple Rockbox experience is to choose a simple theme/WPS for your player, and then just to ignore those features you don't want to be bothered with.
Additionally, though, I think it's a good thing to skim through the manual once before/as you first install, to see what feratures actually are there--you might find that something you want is there. And then, having done so, ignore the rest.