I am mainly a dotnet developer but even I think that if you already have a team full of Java developers there is little to gain from switching to C#. Just the effort of learning a completely new set of libraries and frameworks would give me pause.
C# seems to be the pick for those programmed in microsoft ecosystem in the past, it's not attractive for beginners or non-microsoft-ecosystem developers per se, esp in this cloud and internet era.
I’m dumbfounded that anyone would believe that C# is not attractive for cloud development - Microsoft’s platform or otherwise. C# is a fantastic language and dotnet is a great, modern platform. IMO c# is a tad more beginner friendly than Java.
Also any time I have to use Java I'm always trying to use LINQ before I remember that's a C# feature. C# is really solid, especially .NET Core 3.1 and later.
I think that's unfair to the Streams API. It wasn't intended to solve the same problem as Linq and the problem it does solve it does very well. Streams transform collections. Streams API statements are usually elegant and the party piece of Streams is concurrency with parallelStream(), which will distribute stream operations across threads safely and transparently.
Perhaps java should have a Linq equivalent, but the fact that the Streams API isn't that isn't actually a knock on Streams. In the meantime there is JOOQ and others that deliver elegant query syntax with compile time type safety.
Read the authors argument why they don't use Kotlin, a better language is not always nicer, especially when you risk being left behind. That is the reason why I don't touch C#.
Java has a massive community and a community that shares knowledge. This is what makes Java the greatest tool for any business.