Why kill Sammael?

As the title says: I still don’t understand why they would introduce him only to kill him off three episodes later. I guess it built Moghedien's threat level and maybe you could introduce reincarnations that way. But still.

::: spoiler Tap for spoiler Why take these extra steps if you wanted to condense book material? They could have just cut Sammy and gone with Asmodean right away. :::