This being said, what was really wrong with V3? Is this simply someone's career push ("newer is better, hello promotion!") and is there a su bstantive improvement in quality or security?
By "taxation" you mean wealth redistribution from the wealthy to the state/public right?
It has absolutely nothing to do with "taxation". Initially the reason why Google, Facebook, Twitter and co offered a lot of free API was just growth and user acquisition. Now that they have a significant audience, they don't need third parties to make more money anymore, so no free lunch.
Ultimately these companies won't be much different from Oracle or IBM on the long run.
Sorry, I didn't intend for this to be a political statement, I had a conversation with a right-libertarian friend on the ethics of taxation (I see a need for it) that is still buzzing around in my mind.
By taxation I don't mean wealth redistribution from the wealthy to the state (and certainly not the public, as most of us in the non-wealthy segments pay and don't observe benefit outside of defense and, when not tolled, roads), but rather charge for platform access to citizen rights.
The discussion reminded me of a quote from the US President Obama a few years ago: "If you've got a business—you didn't build that"[0]. His point was that we all build these amazing marvels of technology and modernity on platforms other people provide, be it the state, other companies, and so forth. And because we build these successes on platforms, the platform needs to be funded -- be that taxes, charging, etc.
The crux of Google's issue is that they change their platforms without much warning, without much similarity, and often without prior version support.
Notes
Nothing is free to maintain.