I think of culture as a society's values, traditions, stories, and heritage. Nomadic warfare, gladiators, chivalry, and bushido are part of the cultural heritage of Native Americans, Rome, Europe, and Japan (respectively). These were also inspirations for stories, paintings, and plays. I do recognize culture is a controversial subject.
Something I'm curious about is how many people actually trade away gold-per-turn to AIs? I'm usually trying to get gold
from the AI, not give it away. It's something we could take a poll about. What could the options be?
+20% science while happy is similar to +15% gold from the Commerce opener (though with differences in implementation). The science one mainly helps peaceful players since they tend to stay happy more often. I would be okay with dropping the opener back to 15% science if people feel peaceful research goes too fast in the late game.
Some people dislike free buildings or +production for construction, and the effects are similar (lets us get buildings faster), so I'd like to limit the tree to one of those two effects. Improving science from all specialists instead of only scientists helps reduce the super-science focus in the tree, since we can get the bonus while using a non-scientist specialist.
What if we swap the free scientist with the opener, if most people feel the opener is stronger than the scientist?