Although, looking for painters who are also programmers, but programmers of things other than computer-art systems is also an interesting question. Likewise with musicians, people who are musician-programmers in computer music, and people who are musicians and also programmers separately, might be interesting to consider as different groups.
I think part of this comes from my interest in video games. If you find yourself working as a one man show you'll quickly start developing skills with pixel art (or modeling and texturing if you work in 3D), much as programmers interested in webdev frequently start to pick up skills in graphic design. It would be nice to collaborate with other people and outsource some of these skills, but at the end of the day the best way to get precisely the results you have in mind is to be able to build every component of a project.
I draw cartoons/caricatures (examples here: http://www.smileecards.com) and have painted a few times, but I don't quite call myself a painter.
About teachers, I totally agree that good teachers earn the respect of the students by having high standard, calling students out on bad quality work. I once suspected a teacher only read the beginning and the end of essays, so I submitted a 4 page essay that contained a recipe for banana cake in the second and third pages; I received a B+!