See, that would be fine but the thing is with all those shows you mentioned from before, we already knew that those shows were getting second parts later. The production had already said it. We are not sure whether Decade is getting a second season or not since that article said that it would tell the "whole story" in 30 episodes. But hey, maybe the story will actually be good and entertaining. At least I hope so.
Besides, after seeing the WTF-ness of episode 1, and the fact that the OP is sung by Gackt, I can see that they may not even be able to afford more than 30 episodes.