Why are map values not addressable?

While playing with Go code, I found out that map values are not addressable. For example,

package main
import "fmt"

func main(){
    var mymap map[int]string = make(map[int]string)
    mymap[1] = "One"
    var myptr *string = &mymap[1]
    fmt.Println(*myptr)
}

Generates error

mapaddressable.go:7: cannot take the address of mymap[1]

Whereas, the code,

package main
import "fmt"

func main(){
    var mymap map[int]string = make(map[int]string)
    mymap[1] = "One"
    mystring := mymap[1]
    var myptr *string = &mystring
    fmt.Println(*myptr)
}

works perfectly fine.

Why is this so? Why have the Go developers chosen to make certain values not addressable? Is this a drawback or a feature of the language?

Edit: Being from a C++ background, I am not used to this not addressable trend that seems to be prevalent in Go. For example, the following code works just fine:

#include<iostream>
#include<map>
#include<string>
using namespace std;
int main(){
    map<int,string> mymap;
    mymap[1] = "one";
    string *myptr = &mymap[1];
    cout<<*myptr;
}

It would be nice if somebody could point out why the same addressability cannot be achieved (or intentionally wasn't achieved) in Go.