The goal: to show you only ads for things you care about and are likely to buy and be influenced by advertising for, is good. But the reality is a mess.
Some of the downsides of Google's proposal are obvious, given its position, but there's at least one downside that users might notice: lots more ads targeted only by the demographic of the publication, making the web look more like print media or TV and presenting you and me with a lot more space on our screens wasted showing ads for things you don't care about.
As for the "fingerprinting" proposals? Bad. Very Bad. Think digital "facial" recognition bad.