There has to be a better solution
One of the main themes of Good Omens (the novel, season 1) is that people aren't inherently bad or good. They just make bad or good CHOICES. And having the power to make those choices means they DO have free will.
Now you could argue that power came from eating a certain apple in a certain garden and gaining knowledge about the difference between good and evil. Because you can't choose between two things if you don't know that there are things to choose from.
But I would argue the very ACT of choosing to eat the apple is what gives them that power. It was the first choice they ever made: eat the apple from the forbidden tree, or don't. A choice they only knew about, by the way, because God forbid them from doing it in the first place.
Why put a tree in the middle of the garden with a big “DO NOT TOUCH ” sign on it? Maybe because God was teaching humans how to have free will.
Which is why, in my opinion, the "create a new universe that has free will" reasoning doesn't make any sense. Humans already have free will!
And, what's more, Crowley and Aziraphale are proof that angels and demons do too. They just need a little help learning to exercise it. They need their own apple tree, in their own garden.
But what does that look like?
Well, if we use the same blueprint that Crowley and Aziraphale used… it's living with humans on Earth.
I honestly think there was a misguided attempt to show exactly this in the ending. Season 3's solution to help angels and demons learn to exercise free will is to do away with Heaven and Hell, and instead their souls get reincarnated on Earth. Possibly over multiple lifetimes, similar to the concept in Hinduism/Buddhism, in case they take longer than one lifetime to achieve “enlightenment” (Aziraphale and Crowley took 6000 years, after all).
The problem for me is that, if it does take multiple lifetimes to figure out free will, how can you keep advancing if you can't remember what you learned in a previous life? How can you learn from your mistakes when you don't remember making them?
Maybe the soul itself inherently retains some essence of what it has learned, and with each subsequent reincarnation, it is able to learn more and more. And you could argue that since Crowley and Aziraphale's souls reached enlightenment in the old universe, that is why they are able to find each other, and thus find peace, true happiness, joy and love, every time their souls are reincarnated in the new universe. Which is a beautiful sentiment…
Because while Aziraphale and Crowley did the hard work to achieve their enlightenment, they—their consciousnesses that experienced that hard work—don't get to experience the reward. That's where I think a lot of the anger I'm feeling (and a lot of others are feeling) about the end of season 3 comes from.
Maybe they can't retain their memories because it's not fair for them to get to play by different rules? I suppose if you're going to come up with a new system, it has to work for everyone the same way. Even if it means absolute tragedy for everyone involved.
And to me, this is firmly a tragedy. A Romeo and Juliet level of tragedy. This is not a happy ending. They got their perfect system, sure, but it came at the cost of killing everyone.
There has to be a better solution. Especially because Aziraphale and Crowley proved that it IS possible to achieve their enlightenment in the OLD universe, in the existing system. And because the theme of Good Omens 1 was that the existing system isn't so bad after all. It's actually quite beautiful itself, in its messy, fucked up way.
And the bigger problem for me is the message that this sends about real life. Because real life is messy and fucked up too, but it's the only life we've got. We can't just restart our universe a different way. That's not how it works. And where Good Omens 1 provided comfort to us by saying “that's ok, because our messy, fucked up universe is actually really quite beautiful”, Good Omens 3 said “Never mind, sorry, you got the shit end of the stick but at least your favorite characters get to live in a better world!”
No. No. I don't accept that. It's not the show and book I fell in love with seven years ago. It's not the sentiment I agreed with. It completely negates its original meaning, and it makes me fucking angry.