The appeal of Go is that it has just the bare minimum feature set to be useful for modern backend engineering. It's a language that you can completely fit within your head within a few months of using it, as opposed to certain languages like C++ (or say C# to a lesser but increasing extent) that most will never know completely even after decades of working with it. It's basically the RISC of programming languages.
And if I had to guess, it doesn't have enums so that it can remain flexible when serializing/deserializing enum-like types over the wire. Imagine you can't parse an incoming payload containing an enum field because your service is one version older than the one that extended the enum type (or the enum type is defined in a package dep... you get the idea). Enums are actually a terrible idea now that I think about it.
And if I had to guess, it doesn't have enums so that it can remain flexible when serializing/deserializing enum-like types over the wire. Imagine you can't parse an incoming payload containing an enum field because your service is one version older than the one that extended the enum type (or the enum type is defined in a package dep... you get the idea). Enums are actually a terrible idea now that I think about it.