I really like Archer, but again, it might have to do with me being such a fan of Bakula. I think he carries a lot of his resentment of his father's treatment for so long, and he never gets past that. I think with all of the characters, and I think I might have said this before, so if I did, apologies, that they all needed a rewrite. The established characters were fine, but as you state, they get their setup at the beginning, and go nowhere from there. Even in TNG, you see how everyone, even the fucking android, has some personal growth.
It's weird, because I really do like the series, but it has so many flaws. I think the idea of it is sound, and maybe that's why I latched on to it so well. Perhaps if they brought in a few other writers to expand upon what they established, it could have been a fantastic show. Alas, we never saw what could have been.
I will say, I liked what growth they did get. Trip and T'Pol becoming a couple, and exploring the two of them learning to love each other and put aside their differences. The episode where they found out they had a child, and then dealing with the loss of her, it still kicks me in the gut. Maybe that's just part of being a dad, and having that fear of anything ever happening to my kids.