Shouldn't there be a sponsored link tag ? Perhaps Google should replace those Ads by google with Sponsored Link Tag . That's an answer psychologically perfect . People Don't like ads but find sponsors just fine though both things are meant to be same .
I know what you're saying, but I honestly think that the "Ads by Google" tag doesn't affect CTR in a negative way. If anything, once users see the word "Google", they immediately trust the ad and would be more inclined to click on it than say a regular banner ad.
It may be true or may be not... I think this could be good idea, but I wouldn't expect this from Google...