Now I understand your point better; we were on the same page after vanilla release, remember? I was fierce in that respect, in fact, earning myself a lot of trouble in this very forum. Why do I tell this? Because the only thing no one can accuse me of is complacency.
With that said, I don't know what is going on with your games of BNW, but I am not seeing what you allude to in mine. I am not seeing passive opponents as in "immobilized", but more cautious AI opponents that may or may not become more competitive in the mid-late game because of that. I like that, and I find it makes for much better gameplay, including war-oriented gameplay. What sense does it make to have completely aggressive AI's right from the start when they cripple themselves for the rest of the game by doing so? That's exactly what it was before BNWAI; let's be honest. Who couldn't win an early war against the suicidal AI pre-BNW? In fact, it was a certainty, you just needed to know that they would come, and prepare yourself just enough to be able to hold their suicidal rush but still presenting a target of opportunity so that they would carry on with their early suicide plan. I never found challenge in that. Once the initial suicide was over, the whole mid-late game was yours. No challenge.
What I see now is the opposite. You can feel the AI considering a lot of options (the lot that was hugely increased by BNW). You can see them struggle with the human player for early gold, yet they manage the scarcity well; same with happiness (AI really learnt how to deal with their unhappiness, thus the decrease in semi-cheating bonuses in this regard is completely justified). They really build up trying to be a better opponent for the rest of the game, and not only a fake one for the early game.
Perhaps you need to go longer in your games, or play more, if you did not so already, to see the true evolution of the AI's early decisions? I am seeing that (of course, it does not work for them always, as it does not for the human player in many instances, and that is the challenge), and I like it.