Chrono Cross did not do well in Japan. If you want to talk character development, then Serge, Pierre, Kid, Fargo, Norris, Harle, Lynx, Belthasar, Nikki, Karsh, Dario, etc. more than outnumber Trigger in developed characters. There were just some needless ones alongside that people latch on with accusations that they're representative of the entire game.