>>9572493The "main villain" of Bebop wasn't a single man, it's literally life itself. How it endures and changes and continues on and how we have no real choice but to deal with it and everything it throws at us. He was never really a threat to the crew, just a ghost from Spike's past that needed exorcising. He was barely an antagonist and even less of a character.
Making Spike and then Vicious would be like making the Red Ranger then Goldar and then stopping the line. Yea he was a recurring villain, but people would much rather finish the team then just get the team leader and a single badguy who shows up a handful of times.