Jeremy, There's that old saw: "Let the buyer beware." It's only been fairly recently that the Western world has decided people aren't smart enough to figure out that a woman in a particular ad has skin that's impossibly smooth. Yes, it would be nice if advertisers were completely honest ("Our product is better than some, worse than others, and sometimes just so-so"), but that's not the way the world works, and, frankly, I'd be appalled if advertisers started doing that. It'd create the same kind of hazard nuclear disarmament would create. In an honest advertising environment the liar would be king.
But the UK isn't the only place with boards of busybodies. When I was mayor of Manitou Springs, the Council decided, over my objection, to establish an "historic preservation commission," empowered to do things such as tell you what color to paint your house. I pointed out that if we'd had an historic preservation commission from the beginning we'd all be living in tepees. But I was outvoted, the Board was appointed by the Council, and the Board immediately elected as chairwoman a woman affectionately known around town as "the queen of kitsch." It was all downhill from there, and the damned board still exists and holds back progress year after year.
Maybe what the ASA ought to do is get Adobe to make a special version of ACR without a Clarity slider, and insist that advertisers use that.