Dick Tracy was a decent movie that was burdened with unrealistic expectations. The previous summer, Warner Bros had cleaned up with the first Batman movie. It was a comic book movie with a distinct visual style and a Hollywood legend (Nicholson, not Keaton) in a prominent role. Disney figured lightning would strike twice. They had a comic book movie with a distinct visual. They had 3 Hollywood legends (Beaty, Pacino and Hoffman) and Madonna at the top of her popularity. But while Batman has been a viable comic book superhero for decades, Dick Tracy hadn't been popular in decades. While Batman was designed to be a fun popcorn movie, Dick Tracy was primarily a big budget vanity project for Beaty and his friends.
Disney made the same mistake not long afterwards with the Rocketeer. However, they learned some lessons and didn't put all their eggs in that basket.