To me the biggest step was, when they introduced layers. I don't remember if PS3 had that already, but I remember working without layers in freehand (vector) and it was a pain to mask everything..
I have a tablet too, but like I said... preparing the brushes is too much for me. I have a lot of patience with painting, but for some reason not for that :-b Only make very rough sketches and play with my compositions, as its easy to move things around and make changes..