That is an interesting thought. Defining the service quality minimum acceptable level. As opposed to setting a maximum pricing level (as is the case on LET and LES).
Now I'll sound like one of those guys who come up with a problem for every solution, 🙂 but here are my thoughts on that:
It's not easy to objectively define quality.
A guy wrote a whole book on that (Amazon affiliate link).
Let's take ticket response time for example. That's a simple, straight forward metrics, right? Well - I'm sure we've all had experience with tech. support that responds with "thank you, we'll look into it" or, even when you clearly explain the symptoms and what you tried in order to resolve them, you get "try to reset your computer/modem."
So, maybe we could track and compare ticket response time. But what happens if I post a ticket and go for a ride - while the support needs some further action and/or approval from me in order to proceed?
It's very difficult to objectively quantify hosting quality. And if we decide to be subjective - I've seen some really bad providers perceived as good by some people. And vice-versa for some good providers.
We also should not forget that quality changes over time. HostMantis is one example of a great service gone bad in a few months' time. And there are a few examples of the opposite. It's impossible for even a team of people to keep a track of all that.
What I think is reasonable to achieve is to just weed out the obvious frauds, and share personal experience with the good providers. Maybe I'm too idealistic and still naive, but I believe that in a healthy community, the good ones will be known and stand out, over time.