[metaphysician]

That's not Ant-Man's only problem:

1. Imagery. Most of the more successful super heroes have a solid, iconic look that you can use to make them instantly recognizable. Ant-Man. . . not so much. He's had a million different appearances in the comics, and none of them are particularly striking.

2. Personality. Most of the successful super heroes have a strong personality hook you can use to sell them as characters. Ant-Man. . . has basically no personality of note in the comics that you would want to even consider using in a movie.