There was no way in hell Firaxis was going to fix the AI. They didn't even fix the CIV AI for BTS, that was a community mod they brought in. With the greatly increased complexity of 1upt developing AI was only going to take more time money and effort. Since Firaxis was in no way getting more money why would they go to that extra effort. And Buccaneer, if they don't add features they don't make money, and thus don't work on CIV at all. If you want a good Ai try to start or support an Ai mod. There is only the Fall Patch left for CiV and that will only be a slight fix.
They did a decent compromise with BNW. They fixed the lump sum exploit to no real adverse reaction. They reduced the opportunity cost for swords units. They tried to improve balance and remove player crutches to at least allow more strategies. Since they couldn't fix it, the best solution was to improve gameplay variety. Fixing the incredibly dull and restrictive culture victory, opening up the policy paths, and increasing the benefits of peace all helped that.
I generally agree, I am on record in saying the most important changes (not really features, are they?) were the gold exploits and victory conditions. Also, I understand the economic model, despite my complaints about dumbing down the game to please the masses, and have been an early support of DLC and expansions packs and anything that could keep the programmers programming and artists drawing. In a drastically reduced PC market for gamers, I support them doing whatever to get the resources to develop future DLCs, expansions and full versions. But that doesn't mean I like all of what they chose to spend time on.