A great many people actually like dull girls but i'd say they don't percieve the trait one calls dull dullness. They would call it reliability, predictibility, stability, ingegrity. Take your pick. Jill is more like the last girl standing who is closest to a disney princess type character and there are a great many people who do prefer infact disney princess type characters. Why can't they have their waifu.
If nobody care about the tale of a peasant boy stealing the heart of a princess while competing with a jerk, entitled prince then why so many such tales? Jill's story currently is very similar to that.