I would note that I think devs frequently underestimate casual players.
Particularly if you've got a franchise. If you've played any past installment, you have at least a baseline level of skill much higher than someone brand new, and presumably, about at least 65, 70% will have played a prior civ version.
At a certain point, if you get too simple, you just bore those players.
New players, brand new ones, do have a remarkable capacity to learn. Too frequently it's believed new or casual means idiot who cannot possibly develop. It's not so. It just means new. Players will rapidly adapt to whatever base difficulty is present.
They could throw more at this player base and it'd be fine.