According to former former Capcom artist Katsuya Akitomo, sometime around the late 90's/early 2000's, DC Comics approached Capcom to make a Justice League fighting game. Capcom asked for Mr. Akimoto's opinion and he rejected it. He rejected the idea for three reasons:

1. The power gap between DC characters was bigger compared to that of Marvel.

2. The 90's were a difficult time for the American comic book industry in general, DC in particular was "floundering" outside of the success of Batman.

3. Capcom's development process and the arcade business were in transition at the time, meaning that there were doubts as to whether investing in licensed games would have continued to be a smart investment. For instance, he cited how 2D games were becoming more and more expensive and how they were falling behind when it comes to 3D technologies.
Contributed by ZpaceJ0ck0