This year by year increase in features - what I refer to as the "TV remote effect" - is of concern. Really they ought to concentrate upon consolidating and removing unnecessary features from the language.
This year by year increase in features - what I refer to as the "better than Java effect" - is not of concern. They're not going to remove features from the language, because that would break existing code for no reason, and that would be insane. The only reason to remove a feature is if it can cause damage. Maybe Scheme should get rid of call-with-current-continuation, but I can't think of any features C# needs to get rid of. Can you?
.Net frameworks are not identical to the JVM. The general principle of the JVM is that it remains binary compatible across all versions (this limitation forced severe constraints onto the implementation of java generics, for example). In contrast there are multiple versions of the .Net runtime (CLR) that are not compatible. MS often makes breaking changes across major versions of the CLR.
AFAIK JVM byte code isn't guaranteed to be backwards compatible. They also introduced new byte codes that didn't exist in earlier versions. In that sense, there also are different versions of the JVM.
