I know this thread is a few years old now, but I was wondering if this is an area that had moved forward at all. Is there a chance you will be adding ratings and reviews to the API soon, or a timeline for when you think it might be implemented?
Viewing post in Web API for Ratings
There is already a shitty way to get all reviews/ratings from Itch. I will not explain how (so I don't get banned by angry devs,) but I will hint that https://itch.freezing.top/feed?filter=ratings is a feed of all ratings, and doesn't require you to be logged it. Have fun.
P.S. Anyone who can scrape reviews with the hint was going to figure this out anyway.
P.P.S. Guys, either restrict reviews to be "friends only" (or even "author only") or make a normal API - this is silly.