Why are there so many questions left unanswered in Ben 10?

I mean, first of all, why'd he get Wildvine and Ditto? Why is Sublimino evil? How come me and my friend have a way that Ghostfreak could have the sun destroyed once and for all? Why is Vilgax still alive?How come Ken was smart enough to actually go Grey Matter to take off the limiter but wasn't? Who are Toepick and Shellhead?