While I agree we should spend more time looking at the existing mechanic, I do think it's currently broken.
Even proceeding fully towards a tourism approach (including buying great musicias/writers/artists with faith), I have never come *close* to winning a cultural victory with tourism, while I was able to win the existing social tree way frequently. I always end up building the spaceship instead in BNW. I think there needs to be much more availability of tourism if you focus on it.