Maybe, Sean, or maybe your like/dislike boundary just happens to lie smack in the middle of his oeuvre!
Like Pragmatist, I thought of the major/minor distinction. It may be that Mozart's style, done in a major key, sounds very light to you (an admitted Romantic fan), while the same style done in a minor key sounds deeper and darker and more like what you like about 19th century music. Just a thought.
Also, remember that all composers--at least those who are trying to make a living at it--have to please an audience. That tends to be more true of younger artists, and Mozart was always a young artist. Perhaps you don't like him when he's playing most directly and obviously to his public.
Like Pragmatist, I thought of the major/minor distinction. It may be that Mozart's style, done in a major key, sounds very light to you (an admitted Romantic fan), while the same style done in a minor key sounds deeper and darker and more like what you like about 19th century music. Just a thought.
Also, remember that all composers--at least those who are trying to make a living at it--have to please an audience. That tends to be more true of younger artists, and Mozart was always a young artist. Perhaps you don't like him when he's playing most directly and obviously to his public.