Though that's how it may look, I don't think that was the strategy from the beginning.
I worked as the support engineer for the Google Maps API starting in 2007, in the early days of the API. We didn't think about monetization then. But then the GFC happened, and all over Google, there was a bigger emphasis on monetization -- basically every product had to eventually monetize. We experimented with different types of ads, but as it turns out, map-based advertising is difficult -- it's hard to know why a user is looking at a particular map, it's hard to get advertisers to geo-locate their ads accurately, it's hard to squish ads on a map without adding clutter, etc. While we continued to experiment with ads, we started talking about "ala carte" pricing, letting developers pay-per-view, per-geocode, etc, as a form of monetization.
That was about the time I left Google, when the monetization strategy was still unclear. It looks like they managed to implement ala carte from the technical perspective and decided to introduce it. Though it is a harsh reality check for developers who are already using the Maps API on popular free websites, I think its probably for the best. If I was given the choice between no Maps API at all, a Maps API with (not-so-relevant) ads, and a Maps API with incremental pricing, I'd personally opt for the latter. And who knows, maybe map-based ads will become an option in the future for those who prefer that option.
And if the pricing doesn't work for your site, there are multiple open-source mapping libraries that could use some love to bring them up to par with the Google Maps API (both from the developer & user usability perspective).
I mentioned some in this talk: http://www.slideshare.net/wuzziwug/open-maps-or-close-enough... ...but there have been a few new entries in the space since then.
(Note: As I no longer work for them, nothing I say should be taken as official word from Google.)