Suikoden was the Marvel movies of video games: each title worked as a standalone story, but playing through all of them showed interconnected characters and story arcs. By starting over in a new world, Tierkris abandoned that.
Legacy of Kain was an epic storytelling with an enviable VA cast, but I doubt they could finish it now without Tony Jay as the Elder God.
Ar Tonelico was a great premise, where magical music was the ultimate power in settings of enormous towers over vast wastelands. Qoga was far too fanservice-y though.