I don't think a more narratively conclusive ending makes it more forgettable or less memorable. But I think what a definitive conclusion does do, to the detriment of its story, is that it effectively ends that story as something to think about.
For instance, Breaking Bad. Excellent show, great ending, as conclusive as a series finale can pretty much get. But much as I love that show, it's not something I've really thought much about (other than the occasional "that was a really good show") in the years since. Twin Peaks, on the other hand, finished airing five days ago and I haven't been able to stop reading, writing, or thinking about it since. Maybe that will fade with time (hopefully...I don't think I want to spend the next 25 years still dwelling on Twin Peaks lol) but until then, the open-ended nature of that ending means that the show will be occupying a space in my brain for a while.
Exactly. I haven't been this absorbed in thought about a fictional world since seeing The End of Evangelion as a teenager, an ending that has a lot of similarities and a similar open endedness balanced with bleak conclusiveness (tilted a bit more toward openness than this one). Based on my experience there, I'm going to say that this level of living within the Twin Peaks dream will of course fade with time and we'll move on, but on some level the depth of our reaction to this is going to stick with us for life. This is what it feels like when art really changes you.
17 ended with credits, a quick ad break, and then 18 started with the intro. They didn't roll together like 1 & 2.
Makes sense. I'm trying to imagine the transition between Julie Cruise's angelic voice and Satan himself burning eternally in the hell of hells. It's too broad a gap to bridge for even Lynch.
Why did you find it conclusive?
Firstly, it suggested an infinite recursion. Cooper and Laura are in a cycle where no matter how things superficially change, the core of their existence will not. Any further depiction of their experiences would be superfluous - there's nothing more to be said about them. They are trapped in ambiguity, but the show itself is not,.It's ambiguity is directed toward a greater purpose.
The second reason is this purpose: Lynch using the element of mystery to express a definitive statement and message. We can't live in the world of Twin Peaks and dispel all its mysteries, but at least as far as processing it as a show goes, this statement was so all encompassing that it provided a key to make sense of all that had come before, at least on an emotional and metaphorical level. Even the baffling creative choices start to fall into place because the curtain has been pulled back on the rationale that lead to them and the purpose they serve, at least to my experience of the show.
It's open-ended mystery at the service of commenting on the nature of mystery, in a way broad and deep, and so I was totally satisfied. The book is closed, the author has spoken - there's nothing more to be said. From here, we wake up from the dream and carry the message to our own lives.