Because the shows got progressively worse at they went on. Gransazer started out really good, but after a while, they seemed to had forgotten they had 12 main characters, NOT 4. The plots got really dumb and they started to just recycle monster designs from Godzilla movies. Again though, the biggest problem was the cast was too large for the writers to handle because 90% of the time it revolved around the Flame Tribe rather than any of the other characters, especially after the Water Tribe became good. By Sazer-X, they forgot what made the show good in the first place and went for more crappy slapstic comedy than actually a serious show.