This was indeed a very deliberate choice by Google, and they have been blogging about it since at least 2011[0]. There are quite some blog posts by Google and others discussing the evolution in online maps from the high contrast design focused on roads and cities, to more “fluid” designs where there is a bit more room to show buildings, forests, waterways and other landmarks that are more suited for exploration rather than navigation.
> where there is a bit more room to show buildings, forests, [...]
? What forests and what buildings, though?
The 2009 - 2011 changes are fine, I guess (indeed I don't need the roads that prominently as they were in the 2009 examples), but at some point beyond that they did jump the shark somewhat with their changes.
My personal pet peeve is that at zoom level 14, all distinction between built-up areas and non-built up areas [1] disappears and you're looking at just one indistinct mess of hazy streets on a grey back background and you can't even really tell the shape of a city from looking at that.
Individual buildings only come in at zoom level 17, by which point you're already quite zoomed in, and forests remain stubbornly hidden.
Google has the somewhat better POI integration and traffic information, but when I want to actually look at a map for orienting myself or getting a feel for an area, I much prefer Openstreetmap's style.
[1] At least where I live, the further distinction between forests and non-forested open spaces is rather rudimentary – a few random areas of fields and other open spaces are correctly shown in some sort of ochre at zoom level ≤ 13, but large areas are simply all drawn in green regardless of whether they're actually forests or not.
[0] https://maps.googleblog.com/2011/07/evolving-look-of-google-...