Some intriguing comments from Mark Frost at the Welcome to Twin Peaks web site, which I guess I should look at more often. On The Return:
The themes we were looking at were different. All of that is reflected in the show. I think it’s an older and somewhat sadder and wiser look at the world.
I found the third season somewhat disappointing, but that wasn't the reason. I guess my criticisms are worse, really, because what disappointed me were some of the specific artistic moves. The minimizing of Agent Tammy Preston's role, for instance, for which Mark Frost's book The Secret History of Twin Peaks raised expectations.
And I don't know about "wiser." Darker, for sure.