Danzare,
MAJOR SPOILERS AHEAD
The point for me of the shrinking was to create a Utopia for humanity and save us from our excess waste of resources.
But, it turned into just a way to "cheat" your way into an extravagant lifestyle so the new Utopia was full of the nouveau riche who had suddenly all the wealth they would ever need and nothing to do.
Enter our smuggler character, played amazingly by Christopher Waltz... He is there to provide the suddenly rudderless society with endless drugs, booze, and whatever else is being controlled by the corporation that runs Leisureland.
He doesn't care about size. In fact he let his own brother remain big as his contact on the outside. He only cares about the opportunities there are in this new "wild west" as he describes it. That being said, he turns out to be one of the most likeable characters in the movie.
Then we see the dark side of the utopia: They still need someone to come in and clean up their messes after that day's party is over.
We go to the poor-town outside the walls where the laborers live and see the moral choice the Vietnamese refugee lady makes when it comes to her dying friend.
Then we go to the original little-people settlement in Sweden and it seems at first that they have a true utopia until we start to see that they are a cult like any other.
The smuggler says it best when the choice comes to survive underground or face the environmental disaster to come: "They'll be at each other's throats killing one another within 50 years and we'll still be here for at least the next 300."
Our main character, who has always been drawn towards helping others, goes back to Leisureland and becomes a permanent helper in the Vietnamese lady's "meals-on-wheels" effort.
He hasn't helped save the entire future of the world like he briefly wanted to, but he is taking care of the living for now. He has found peace... And then she honks the horn for him to hurry up... The end.
I thought it was an excellent movie mostly because it didn't focus on the point of people being shrunk.
It was more like, the more things change the more they stay the same.
I was so glad it wasn't just a movie-long episode of Land Of The Giants.
I'll hide this part, so as to not spoil it for anyone who wants to watch the film.
Now that's you've described the movie by including the shrinking, let me explain it to you without the shrinking.
Guy divorces his wife and then meets a smuggler in his apartment building who uses illegal immigrants as hired help. He then sees the dark side of the world when he gets to know one of these people. The smuggler turns out to be a pretty decent guy. He then gets invited to go to this place which is supposedly a paradise, only to find out that they're a bit of a cult who has an underground bunker, because they think the world is going to end.
You can literally have the exact same film play out (minus the first fifteen minutes) without having shrinking in it.
(As a matter of fact, I wouldn't be surprised if that film has already been made.)
I hated the movie, because it didn't focus on what people were clearly sacrificing by being shrunk down. They were literally selling their freedom and security, for money. They were all relying heavily upon big people to accommodate them, and it was clear at the start, that some people had a problem with that.
I wanted to see the inevitable conclusion of it all. The sad ending where it all falls apart for our main character as the shrinking fad inevitably dies!
I wanted to see the passage of time, the lack of maintenance on Leisureland, the increased prices of miniature products. The people who were shrunk and got lots of money as a result, suddenly ending up on the bottom of the food chain. Rats and cockroaches breaking in. Perhaps even a psychopath (who is big) breaking in early on in the movie, screaming about how he hates little people, and smashing half the city under his foot.
I wanted to see them be abandoned, as you got to see the true dark side of reality, when the inevitable bubble pops. And how greed had fueled it all.
You can't tell me that would've made a worse movie.
You said you like how it was a movie about how the more things change, the more they stay the same. Which proves my point exactly, as it is just a fancy way of saying, the shrinking added nothing. You could have just as easily replaced shrinking with anything else (going to Mars for example) and had the same film. Or as I have said multiple times already, you could've easily removed it entirely!
I believe if you are going to add something major into the story, it should be integral to the story. Any film can say "Oh, and it's set on mars in the future", but it doesn't instantly make it better. Could you imagine if they did that to The Usual Suspects or Pulp Fiction? Would it have made those films better or worse? In my opinion, worse.

That being said, I'm also glad it wasn't just a movie-long episode of Land of the Giants. Or a remake of Honey I Shrunk the Kids. But come on, if you're going to introduce the social changes caused by people shrinking themselves, you've got to follow through with it. Don't just have it as a backdrop.