Most of the fear about this new development - which has lots of precedent as you point out - comes from the media outlets for whom this is another nail in their coffin. Maybe you're agreeing with me on this (it's not entirely clear to me), but I think Google becoming the highway patrol means they've crossed a line not yet crossed before, one that I think will give them enough power that they probably can't resist using it on their ad competitors. I worry that the reverberations will be felt in many more places than just at media companies that should've been dead already - if your 30% suddenly became 18%, I think you'd notice. I'd actually love to know what ad agencies think of this, especially since you posted a while ago about how they hate how online (video) ads are organized these days.
Thing of it is, if your news isn't in an app wrapper by now, you're already dead. NYT. WaPo. Chicago Tribune. LA Times. Albuquerque Journal. Yeah, it's a line not yet crossed but if you're still out on the field instead of in the silo you already missed the harvest. The Do-Not-Call list had a seismic effect on telemarketers but nobody cared that much because everyone hated them. Unconstitutional? mos def. But it still happened and nobody mourned. Banner ads are gonna be the same way. How do marketers feel? If they had any faith in CPM they wouldn't have thrown all their efforts into viral advertising.