But please consider the fact that without nightmare moon, there'll be no MLP.

Nightmare Moon is part of Luna's character, I'm sorry to say. Without Nightmare Moon, episodes like Luna Eclipsed, Do Princesses Dream of Magic Sheep?, and A Royal Problem would make no sense. Neither would the biggest part of Luna's character arc for that matter. 

I think characters with flaws are a lot more interesting than ones without them! I prefer Luna to Nightmare Moon, but as with several other characters (Starlight, Trixie, Sunset...), their past really shows how they've improved from their past selves.

Also, that they've reconciled really shows how strong the bond between Celestia and Luna is, in spite of everything that happened (both Luna becoming Nightmare Moon and Celestia's decision to banish her).

@CloudMistDragon @Tacodidra I just wish that Celestia and Luna didn’t have to suffer the way that they did. They managed to pull through in the end, but it’s just that the whole situation is very sad and painful to hear about!

And that's what makes it so tragic. Young siblings failing to communicate with each other resulting in them being separated for a 1000 years. Celestia paid for her arrogance and not thinking about how her sister felt by being alone for a very long time. She had no one to confide in with what she had done. That's a long time to carry grief and regret over what happened. Celestia had to choose between the well-being of all the ponies and her sister. That is not a choice that any family member should have to make. It was the first time that Celestia had tried using all the elements at the same time. Normally should would only use three (like Luna). I think she was unprepared for the power of using them all at once and meant to subdue Nightmare Moon, not imprison her for a 1000 years.

1 hour ago, Twilight Luna said:

And that's what makes it so tragic. Young siblings failing to communicate with each other resulting in them being separated for a 1000 years. Celestia paid for her arrogance and not thinking about how her sister felt by being alone for a very long time. She had no one to confide in with what she had done. That's a long time to carry grief and regret over what happened. Celestia had to choose between the well-being of all the ponies and her sister. That is not a choice that any family member should have to make. It was the first time that Celestia had tried using all the elements at the same time. Normally should would only use three (like Luna). I think she was unprepared for the power of using them all at once and meant to subdue Nightmare Moon, not imprison her for a 1000 years.

But even then, even after those 1000 years apart, Celestia still forgave Luna for all that had happened! Why? Because they’re sisters and that’s all that matters!

So just think how much greater their lives would have been if Nightmare Moon never existed!

There's a LOT I can say about this, but it will have to wait. Not enough time right now. But I think that Nightmare Moon played a critical role in MLP becoming what it was.

It also tells us an important lesson right from the beginning; something that even old mythology never had an issue with portraying. NOBODY is perfect. Not even the gods. We all make mistakes. And sometimes we only find ourselves after being put through the fire.

Alright... granted, this is coming from a relative noob. But after I caught the "bug," I did a lot of reading on what others have said about their experiences. This just feels right.

Going back to 2010. It was a pretty dark time. Really, most of entertainment had gone full grimdark. We were living in the post 9/11 wartorn world and hadn't recovered. Society felt dead to many of us, like the life was a hoax. Nothing to feel happy or good about. Deep down, we wanted a different world, something with heart, where people could have feelings, but it wasn't given to us. We became jaded and angry that nobody else could see the beauty that we knew was there hidden. Nobody else ever saw it because they were 'asleep.' And one by one, we all exiled ourselves to a mental prison, to shield ourselves from everything outside. A self-imposed lunar exile for... pretty much everyone. The rise of the "emo goth"  is a very physical testament to this.

Then comes S1E1/2. MLP, a silver lining in the metaphorical sea of darkness. It's all too perfect to me, to think that MLP began with the story of Nightmare Moon. She was so many of us before we discovered Ponies. A broken shell of our true selves created by forces beyond our control. But then we sit down and watch. We know the backstory, how Nightmare Moon was created. We see ourselves in it. And then the very next thing we get is an olive branch. We're shown something that we once knew, but had forgotten about, that the most powerful force in the world is friendship. And we're shown something that our psyche has never before experienced. "It's okay now. Things are different now. You can come home."

I, myself even had an evil villain counterpart that I actually created as a result of what I was experiencing back then. But it need not be so accurate. Nightmare Moon was so many of us. Just waiting to know when we could return to the world. For me, the salvation of Nightmare Moon couldn't possibly be a more perfect beginning for this fandom.