I don't know but I always found Google's font choice, airy cold, disconnected and vapid. Not sure why I get that response but something just feels incredibly stale and impersonal.
I don’t mean that to seem unkind or critical of the people behind the design; they’re clearly very talented and far more than I am where design is concerned. It isn’t meant to be disparaging. People clearly like it, but for me personally it has always felt like it lacks any kind of soul or energy.
Material UI is the safe choice that you can pick up and implement while assuming users will be able to figure it out and won't really have ground to complain too much about it. Material is becoming the universal "good-enough" UI and work like that being discussed in this post are efforts to fill in those last few gaps where you have to break out of the standard Material UI model because your use case isn't covered.
MD1 told designers to embrace unconventional, bright, saturated colors and contrasting pairings. They even had a blog article reassuring that, yes, your brand can survive the material redesign.
MD2 embraced brand specific designs with custom fonts, button shapes and, again, waay too many colors. There where "Material Studies" [1], in which they show how a brand could adopt the design system. For the Google flavor of MD2 they threw away all of that and went with white.
MD3 shifts again, to pastel colors and user customization. It corrects many mistakes, but I believe third party apps won't like having to account for all the possible background colors.
To me, the first two versions are a failure [2]. They were amazing to read, but the real world turned out different. Compare this to the Human Interface Guidelines which have stayed far more stable and neutral.
[1]: https://material.io/design/introduction#theming [2]: In the sense that what they set out to achieve led to completely different results in the real world. I'm not saying that all Android design since Lollipop is terrible.