Call me crazy, but the Alien is kind of an important element of the Alien franchise. I love hearing Scott talk about his experience with the first film, but as far as his ideas regarding the franchise now and where to take it, couldn't disagree more. I think the 40th Anniversary shorts and Alien Isolation both proved his hypothesis incorrect.
So essentially - "Hey Ridley! There's still life in the Alien! Just look at these short films and video game that are highly derivative of that movie you made. Just make that movie you made again."
You know you can disagree with an opinion without shitting on it, yeah?
They were derivative in terms of style and tone for sure, they still told intriguing new stories with new characters and expanded the universe in a way that most enjoyed. Prometheus and Covenant were pretty derivative themselves in terms of following the story beats of Alien...
People discover signal/map > land on planet > explore derelict spacecraft > come into contact with contagion > infected crew-member dies in dramatic fashion > remaining crew must survive against threat.
Now Alien, Prometheus, and Covenant have different themes they explore, and styles they present, but on a basic level, Scott remade Alien twice, with two of them vastly inferior to the first.
Do I think Scott should finish his trilogy? I'm really torn on that one, perhaps half of the fan-base (I'd guess) enjoyed the prequels, and yeah it's not fair to them to have such a cliff-hanger not followed through on. It's a bad look for the franchise as well to leave such massive set ups without payoffs. Still, I personally feel enough damage has been done to the mystery of Alien and the Space Jockey that whatever Scott has planned next could prove even more divisive than Prometheus and Covenant have.
I think the franchise can try new things for sure, but this is kind of like hearing JJ Abrams talk about how he didn't like Star Trek while directing the reboot... 'why are you making a Star Trek movie then?'