That’s a really good analysis of the characters. The reason I didn’t feel the same kind of outrage about Season 5 that I felt about Season 7 was because Ramsay had so little influence over the direction of the story. He simply gave the North a little something to do (along with all the torture porn), until Jon became Lord Commander of the Night’s Watch and made his deal with the Wildlings.
In the books, Ramsay marries a girl who is pretending to be Arya, and there’s very little description of Theon’s torture, just hints about it. This was one of those areas where D&D ran out of source material early on, explaining the loss of direction and falling back on villain clichés.
I tried the thought experiment of rewatching the series finale as if the last episode was Season 7 Episode 1. From that perspective, the last episode was really good, delivering on all the foreshadowing and character arcs created over the first five books.