"I'd've said it was valid as long as the writer's putting them in a suitable context - like after the first batch, it says summat about members of the public's comments (or similar). Tho of course it suggests the gen public are likely to be interested & thoughtful enough to make those sorts of intelligent comment - which I'm unconvinced about...."

That's the point, I think. Quoting from here is very valid if its made clear they are grass roots quotes - but not of the "mass observation" or "man on the bus" type - more "opinions of the informed public" type of thing (though something a bit less boastful than that.) "The Public", after all, probably thinks the Druids built Stonehenge...