Also, I think you're conflating legality and morality. I can think of situations for all 8 cases of (legal|illegal)(moral|immoral)(agree|disagree). However, you're probably right that agreement/disagreement influences morality judgments.
I do not know about Shakespeare 'breaking' any rules, or any pre-XIX Century painter. Or the Greeks, you know? What rules did the Parthenon's architect break? Or the sculptor of the Laocoon group?
The 'breaking rules' stuff is all very well for some things but it is not the definition of art. Please.
(Spanish examples because I am a Spaniard, but you understand).
Edit: romantical/romantic.
Possibly the 'please' in my comment is paternalistic, but then again your definition of the job of an artist is quite simplistic. So it may not be paternalistic but a plea for sensible speculation.
I guess my general point is that to be an artist, you have to be creative. To be creative, you have to do something new. To do something new, you have to depart from what exists in some way. Whatever exists can be called authority, tradition, or "the rules". And then something new is a challenge to that authority. If you build a skyscraper in a town with no skyscrapers, you are challenging authority, even if all the other towns have skyscrapers. When parents make a baby, it's a creative act, and the baby ends up challenging the authority of the parents; the baby breaks the existing rules of the family structure. It's the same with the work that an artist does. It doesn't have to be socially rebellious in nature. An expression of beauty that has not been seen before is breaking the rules about the limits of beauty.
Even more generally speaking, when an artist does manage to break the rules, they end up challenging our preconceptions of what can be - these preconceptions are the true "rules" - and it opens us up to a deeper experience of the world. As examples, anything that creates a feeling of awe, anything that touches on sublime beauty, is operating on this level. I think if you look closely, all of the artists you named are working in this way; it's not mere repetition of what came before.