Because she wanted people to think that she killed him? I don't know, I'm just saying, there was no reason not to show her actually killing him (because of people like me). On a show where they actually DO show a death and it turns out to not be a true death (Jon) ya gotta show those deaths onscreen.

I completely disagree that Stannis' death was made unambiguous. If anything, this reveal makes it more likely that he is still alive. Unless I see a dead body, they are alive to me!

It wasn't originally supposed to be a mini series. Their order was cut and the show was essentially canceled during shooting.