Ad-blockers / cross-site request blockers / script-blockers should be considered a big part of modern Anti-virus technology, essential to browse the web in safety. What Google plans to do is utterly irresponsible and is only to cater to their own ad business, finally completely tilting the scales in the corporation's benefit to the detriment of hundreds of millions of people. This is not an open web, what Google wants is an appified web, a closed system that you can't inspect and filter. In essence, more in line with their store walled garden.
History tends to repeat itself when given the same circumstances. Microsoft exerted all its market power back in the beginning of the century with Internet Explorer 6, and now that Google is the new Microsoft (with Microsoft adopting the Chrome engine inside Edge, no less), they are going to try to do it too. "Be unavoidably evil", that's in practice their new mantra.
The cross-site request system as it currently stands exists for several reasons, one of them being maximising user tracking and profiling directly, but also because companies don't trust each other to have data relayed to them second hand to determine ad related payments. So, it's kind of rich for these companies and Google at the top among them, to pretend to assume that people on the other end of the line (Internet surfers) will be perfectly fine with trusting almost everything that comes from a bunch of people who don't trust each other.