[foldr]

They took the time to do it properly with input from experts on type systems (e.g Phil Wadler). The result is probably much better than what we'd have if the Go developers had quickly thrown together an implementation of generics 10-15 years ago. For example, the resulting type system is known to be sound.

[kaba0]

Now it may be close to Java’s expressivity, 8 years ago. Now if they manage to cut down on verbosity it might surpass Java 8! How advanced!

[foldr]

Java's generics implementation is certainly much more expressive as it's unsound :)

People can write Java if they prefer. No programming language is going to please everyone.