Painting directly on the plastic looks like a great way to finish these kits. Very nice weathering - BUT... risking sounding like an douche I'd be remiss if I didn't mention seeing what I think are fingerprints here and there. I am sure it's not as visible looking at the figure irl when it's not all zoomed in like that. If it is fingerprints I'd suggest washing the kit with soap before painting so there is no finger oils or other residue left on the surface from handling. One glove for the handling hand during painting is my goto