I don’t know if I’m in the minority or not here, but I fundamentally agree with Ivan’s messages, especially around Google’s tiles. Let’s face it, they key thing users/developers want that they have is the cartography: it is not only extremely well-done (especially in the “satellite with labels” tileset), but users are so familiar with their stuff, it’s almost a “standard”. Of course Mapbox and several other commercial providers make beautiful maps, too, but Google has a long lead.
Of course, I recognize that Google also has a business model to protect. So what if they published a version of their tile sets that could be used outside of their API? Maybe it lags a few months in updates, has less (or more?) “commercialized” data points, has different rate limits, or something like that. They get to keep some of the fundamental value-added pieces (geocoding, place search) inside their API and still gain some good will.
I’m not sure if I buy that a new MapML standard will really help the web. I think I probably have a bias because I don’t find existing mapping libraries “too hard” to work with. There are so many more choices today than there were in ~2006 when I first started making slippy maps, and I think that’s a good thing.