Originally Posted by Starwulf
While I can agree with that, according to Fri, Durarara has other books that haven't been adapted into anime, and where they cut the anime off is apparently just where it starts to get really good. So, I can't say I support that kind of decision, to just arbitrarily cut off an anime when there is apparently significant amount of plot(and good plot at that) left.
What if the books aren't finished? This is very
common. Anime burns through material at an alarming place, and can overtake the source very quickly - in that case you have to make up an ending or use filler to delay until more comes along.
And how often do you think they can leave the contracts for completion of the show that open? A long anime is a big investment, which could flop.
Plus, you can just read the source material. Assuming you're Japanese.