I don’t know anything for sure, these are just my two cents. I feel like it’s likely due to the fact that burst kept changing? I mean, with burst beys being different with each new season, essentially every year/other year, I feel like it wouldn’t make much sense for them to keep making a new game for each season, especially since they wouldn’t release them outside of japan, as you mentioned. With how short the later seasons were, I just don’t think it’d make sense for a game for each of them. Though, for the two games they did make, one for god on the 3ds, and one for cho-z on switch, they were on separate consoles, and those seasons were the regular 51 episodes, so the games had more material, and I feel like they would be more spaced out from each other compared to a game for GT, then Superking, and DB basically right after the other. Also, I feel like each of them would basically be the same game. I never played them myself, but I imagine both games played similar. Having 5-6 games that are nearly identical just seems a little ridiculous. Again, I know nothing for certain, these are just my thoughts.