They had to rerun the films, for the people who can't afford to make it to a theater or buy a damn DVD. The concept of Saiyan God takes a completely new direction in terms of creativity, whereas SSj4 is just a rehash of the original Super Saiyan concept. The introduction of new Universes and a complete new hierarchy in Dragonball also expands the universe, whereas GT does no such thing.
I don't even think GT can touch Super in terms of creativity, simply because Toei handicapped the show, whereas Toriyama has the freedom to have his influence, to a much greater degree than he did with GT. Hell, GT was receiving terrible reviews and it only picked up pace until Toriyama got involved, that speaks loads.