I think that a couple of reasons why Go is easy to learn are:

• Not too many magical syntactic sugars.
• Unlike other old and still evolving languages, there are usually not more than one way to solve the same problem. For instance, you can now define a getter/setter in 4 different ways in C#. A language that requires so much memorization is not an easy one to learn, especially when you are required to write idiomatic codes in that language.