My pure conjecture is that they lost their focus and began winding down seeing the end come. The last season seemed a little assembly line, a little dull, and a little distracted to me. I think a lot of series tend to get dull in later seasons too comfortable with themselves and having lost some of the fire and new ideas of earlier seasons. S7 had some pretty unique episodes but they sort of just fell flat with me. And some of TPTB I remember saying were distracted putting together GEN.