In some cases, if you have long-lived services, then Java and .Net make sense... You can get farther with the code in place. If you are running one-off executable handlers, that need to start and finish quickly, then you probably would favor go.
It's entirely possible for different options to be part of a larger solution.. and while I agree, the lack of generics is truly painful... I remember C# before, and feel that Java's generics are a horrible implementation... I'd rather wait for a nice implementation just the same.