i wish ctr weren't weighed so heavily, i'd rather it be relevancy... in some cases, off target ads from a super strong brand or something click worthy bring irrelevant results that get clicked - and there you sit with a horrid qs wondering why your on target ad and product and page are whacked for low qs. it's frustrating! g doesn't mind throwing a shiny object across the room if people click on it - long term, i think they'd be better served themselves by putting shiny less relevant things into a separate boxed area.
the overall account ctr scoring is also a shame - if they listened to people running ppc, they'd realize they are inadvertently complicit in trademark poaching by rewarding those who don't do deep product marketing, but just scalp name traffic (very high ctr), often against the merchant's terms of service. if g allowed simple guards against third parties dropping certain traffic, their big clients would see a higher cpa / roi and spend more driving deeper - so it's also a bad biz move by g to not provide tools to make managing your allowed ad partners more easily... and it would make no diff to the consumer.
ctr ain't perfect, but as a consumer, it sure beats a price auction (without qs) where spammy ads would litter, and ppc would be a contest of who will go furthest to buy share.