@Juan63 Yes, more explanation of why a rating was given would certainly be helpful. I might rate a guest low on communication because I'm a home-share host and although the guest answered pre-arrival messages and gave their ETA accurately, they might be socially inept and and a poor communicator face-to-face, which isn't a good fit for a home-share. But entire-home listing hosts wouldn't necessarily be fussed about that aspect of communication skills.
Personally, I would like to see star ratings eliminated entirely, because they are so subjective, and, as you say, there is no explanation. And non-IB hosts can't even see guest star ratings, which I don't understand at all, it just seems like a punishment for not using IB. Whereas a written review makes things clearer and hosts can judge for themselves if something one host objected to would be an issue for them.
This obsession with star ratings these days, where people are asked to rate everything from their restaurant meal, to the place that changed their tires, to the service they got from the bank teller, is way over-the-top, IMO.
If there were a function to leave an explanation, I wouldn't want it to be multiple choice, because I just know the choices Airbnb would give would be inadequate. Have you ever gotten one of their rating questionnaires after dealing with CS? The first question is (maybe not an exact quote) "Based on your interaction with XX, how likely are you to recommend Airbnb?" Well, I would never recommend or not recommend a place or a service based on my interaction with one employee, so that question is just stupid and irrelevant to me.