I'm with you, both for your reasons and for another: it makes code harder to teach. "Oh, you'll see this. And this. And this . . . There's this, but no writes it that way. This is idiomatic."
There's some of this in all languages, of course, but "this bit of sugar will make the code cleaner and easier to read" assumes that everyone will adopt a new set of idioms wholesale (which they usually don't).
I have spent a large portion of my career teaching new developers. I think C# is a pretty terrible first language already. The sugar here and there is nothing compared to the massive mental burden of OO, inheritance, compilation, DLLs, Visual Studio, etc etc etc.
Scheme, via SICP, is much easier to get started with, and one can learn the basics with that quickly (including getting much more comfortable with the sequence abstractions -called LINQ in .NET- than even the average .NET developer).
All these reasons are also why I greatly prefer F#. If you stay away from much of the OO system, F# is much simpler to teach in my experience. At my company right now another team is putting together an F# training program intended to teach our QA automation.
There's some of this in all languages, of course, but "this bit of sugar will make the code cleaner and easier to read" assumes that everyone will adopt a new set of idioms wholesale (which they usually don't).