There can be insight there (one great property of startups en masse is that they serve as a great experimental method for proving zanier ideas will work or market segments can exist if a product is made for them), but there does come a point where it's like saying Google's success in AI research is because they spotted AI researchers and snapped them up. Well...yeah, employees usually are hired for the job they were hired for.
Regardless, the original poster's criteria was "Google continues to validate its service not by competing on quality or feature distinction, but by throwing gobs of cash at it", which I think the GP's examples clearly contradict, as all of them have continued to gain quality (for some people's definition of quality) and feature distinctiveness.
To take the tangent further off topic it's interesting to me that Google's greatest successes post-search/ads appear to be these strategic products. Not things that bring direct profits, but those that allow them to influence the major platforms (mobile, web). Committing key resources in this way speaks of long-term thinking that other companies could learn from.
Least of all after witnessing the random price changes with App Engine, there's no reason to believe this low pricing is for the long term, so it's not like this is even good for consumers.