If one of the richest companies on the planet can't pay to hire good designers, and just pay to buyout a whole ecosystem (ie what they did with AMP), then no one can.
Rather, I think your points aside, it's a matter of executive direction and attention. Google executives doesn't give a damn about good UI. They have all the money in the world, but won't spend it on proper improvements to UI and product interfaces.
You can argue until your face is blue that the people at Google are great, very talented, but unfortunately ... if the execs don't buy into it all these talented designers/engineers are just twiddling their thumbs and making design mocks that will never see the light of day.
Or as the saying goes: have their product cancelled once they make it a good product.