map in Go is already generic. If you need map[string]int or map[int]float, you can already do it.

Generics do not obviate the need for interface{} or the described use case of map[string]interface{}

interface{} is like Java or C# object. It packages a type and a value in a single value that can be queried at runtime to extract the underlying value in a type safe matter.

When people use map[string]interface{] it's because they don't know the type of value at compile time.