I'm a very experienced Unity C# programmer, and I certainly don't equate "good" with using all the new fancy features of a language.

Fancy features are less maintainable imo. Less programmers will know about them and they're less likely to have equivalents in other languages.

Making something more exotic / confusing / hard to parse is defo not worth saving a few lines of code.. I'd much rather see a longer function using absolute bog standard elements of the language (and thus being clear, easy to comprehend for everyone, easy to modify at any point) rather than a super short, super "elegant", super "clever" solution.

Languages that seem to indefinitely grow more features over time (like c++, c#, rust, etc) evitably become bucketed by epochs unless the consuming application code also operate across the same time scales. Feature deprecations tend to go hand in hand with newer features, leaving you with basically "multiple sublanguages" in a supposed single language, exacerbating fragmentation of the community. I don't want to have the mental load of contextually understanding "which" sublanguages I need to care about depending on the year a consuming application was written. This is why I tend not to reach for new fangled features and stay with the core runtime stuff in evergreen langs.