The only cartoons that do that are those based on card games and interactive toys (Pokémon, Beyblade, Tenkai Knights, etc.), and even then they're not that different from shows which just introduce new characters and story arcs along the course of their run.Yes, I wouldn't want a Trek show to depend on selling toys, either. That would almost certainly generate episodes that I would not enjoy watching.
So, did you just ignore what I said about Young Justice and Green Lantern? I'm not going to go dredging up links, including those to all the articles that got discussed in those threads, but here's one link anyway.