Why javac does not optimize even simple code?

Question

Given the following code:

public class MainClass {
    public static int f(){
        int i=0;
        i++;
        return i;
    }
}

the c

Answer 1

Also, by moving optimization to JVM, all JVM based languages can benefit. Compilers (not just javac) have a relatively easier job; language inventors don't have to be optimization experts.