This has nothing to do with my -- or your -- anecdotal experience. The box office numbers simply don't bare that out.
"People didn't know Man of Steel was a Superman movie because 'Superman was in the title" is one of those theories that sounds good, but doesn't reflect the facts at the time.
- As I noted, Warner Brothers spent ~$75 million promoting the film domestically, beginning with two different teaser trailers that ran before The Dark Knight Rises a full _11 months_ before its release. If you saw Dark Knight Rises, you knew this was a Superman film. Period.
- As I noted, Man of Steel made money domestically than Superman III, Superman IV, or Superman Returns -- even after adjusting for inflation.
- It was the number five box office film of the entire year, in a year that included Frozen, Iron Man 3. and the most successful Hunger Games film.
- It was also one of only three films that year to open to more than $100 million domestically -- the other two were (naturally) The Hunger Games: Catching Fire and Iron Man 3.