@Iryna52 If guests used the value rating correctly, rather than it indicating that they'd have preferred to stay for free, don't appreciate anything, and are clueless about the work and expenses that go into hosting, it wouldn't be a bad rating category.
For instance, while many hosts really aren't charging enough for what they provide, whether that is due to high competition in their area, following Airbnbs absurd price tips, or simply undervaluing their own time and effort, there are others who are charging more than they deserve.
I had a very nice guest who has used Airbnb a lot, and when he left his review (all 5*s), he sent a private message that said, "That was one of the best Airbnb stays I've had. You wouldn't believe the crap some people list and actually expect money for".
I don't agree that value is something guests can assess when they book. The place may look nice in photos, and provide the amenities advertised, but in reality the bed is uncomfortable, the pillows old and flat, the sheets pilly, the towels scratchy and stained, the cookware old scratched up teflon, etc.
If they've picked the cheapest listing out there, the price of a hostel room or less, they really have nothing to complain about re value, but that isn't always the case.