While there are many points in your post that I agree with, we really should stop worrying about how people dress.
If it's a developer sitting behind a computer screen all day long with zero customer contact whatsoever, he really shouldn't be forced to wear a certain dress code just to satisfy someone's standard of professionalism. Such feelings are in similar spirit as "woman should not wear trousers" a few decades ago - there is just no rationale behind it other than conditioning by society.