That was a smart move. They were able to tweak plot lines moving in directions they must have had second thoughts about -- for example, Jack has a love life again (although with the wrong lady). Deputy Jo was stopped from marrying Zane, a good move. Replacing Allison as head of Global Dynamics with Fargo, of all people! That should be fun. And a new character was added to the mix -- Dr. Grant, who worked with Einstein but now has to play catch-up. However, it was Allison's son Kevin who pretty much guaranteed they wouldn't be able to undo the changes they made. They couldn't send a normal, healthy kid back into his original autistic state.
Notice they did not bring Zoe back? That was smart, too.