Board Thread:Spoilers!/@comment-6175354-20141215234519/@comment-5899967-20150213175921

I think of this like sagas... the comparison may be weird, but Dragon Ball Z also kills most of its main villains when their arc is over.

The reason why Regina, Hook and Rumple are alive (for now), is because they are main characters, the story focuses on their journey from season 1 (S2 in Hook's case) until the end. The other villains have their own saga, though they don't necessarily have to die. Jafar is still alive for example, but my gut feeling says he'll die if he appears in the main series.