Just to give my 2 cents, I can't help but wonder if the culture policy requirement for wonders is necessarily the best solution to the problem. For one thing, I think it's a little counter-intuitive and adds another thing to keep track of and remember. I don't just mean that wonders require policies, but the exact number of policies each wonder takes.
I haven't played in a while and am only at turn 70 (on Epic speed) in my most recent game, but already I feel that having different numbers of policies required for different wonders makes strategizing more difficult and time consuming. If you have to keep going back to the tech tree or Civilopedia over and over until you start to remember some seemingly arbitrary numbers, it's easy to be overwhelmed.
I say this as a player with only a little experience with the CPP. Still, my logic is that, if I can't imagine explaining this mechanic to my moderately-skilled vanilla-civ player friend without getting weird looks, it's probably overcomplicated.
If I understand correctly, the reason for this change was that tech-leading civs tended to runaway with all the wonders because tech was the only thing unlocking them? If that's the case, I'm sure some brainstorming could come up with a simpler and more intuitive solution. Even something as simple as making all wonders require more production would make it so that building lots of wonders would set you back in other areas, and would encourage players and AI to only build what is actually helpful. Another idea is that the more wonders you have, the more production successive wonders cost. It more of a forced solution but it's hard to deny that it accomplishes the goal simply, and even with some arbitrary scales and numbers, there would be nothing really necessary to keep track of at the time of building.
Also not sure I'm thrilled with the yield-into-science mechanic either, though I'll give it a fair shot. Again though, as a solution it seems a bit like using a sledgehammer to squash an ant.