Idiomatic design will never come back. The reason being companies believe (correctly) that they design language is part of their brand. The uniqueness is, basically, the point.

That was one of the problem with the original Material framework: every app looked too similar making it hard to distinguish one from another. Google was concerned about people associating bad third party app with itself.

They added more customizability in Material 2 (or was it 3?), but yeah at that point some of the damage was done.