I can definitely see the idea behind this, but I have to say I'm glad I never experienced this in school myself. Certainly one should use the most appropriate and expressive words for the meaning they're trying to convey, rather than as you point out much blander words like "good" and "bad," but I also think there shouldn't really be parameters as to the specific words that must be avoided at all costs. Some of our best writers - I'm thinking particularly of certain midcentury authors - use quite simple, matter of fact language, and it doesn't in any way detract from their writing. That's just my opinion though. At any rate, a really interesting piece, Ben!