What are the runtime advantages of using Java generics?

Question

I have downloaded Build 31 (courtesy of JavaLobby) and compiled the following program.
Both methods (main and main2) are compiled to the exact same bytecodes (use javap -c to dump the bytecodes). I believe that the generics version (main) is clearer and cleaner (I regularly use templates in my C++ programs), but for the JVM they are exactly the same thing.
Why did not the JVM was slightly modified to support without using erasure (the checkcast opcode that is used in compiling (String) it.next() could be eliminated in for (String v : s) )?
// Compile with: javac -source 1.5 Test15.java
import java.util.*;
public class Test15 {
     public static void main2(String[] args) {
          Set s = new TreeSet();
          s.add("one");
          s.add("two");
          s.add("three");
          for (Iterator it = s.iterator(); it.hasNext(); ) {
               String v = (String)it.next();
               System.out.println (v);
     public static void main(String[] args) {
          Set<String> s = new TreeSet<String>();
          s.add("one");
          s.add("two");
          s.add("three");
          for (String v : s) {
               System.out.println (v);

Answer 1

It is not meant to be faster than the normal approach, it is meant to be easier to implement and more secure.
Why did not the JVM was slightly modified to support without using erasure
(the checkcast opcode that is used in compiling (String) it.next() could be
eliminated in for (String v : s) )?I agree, and more do, that the erasure is somewhat the wrong approach, however, the JSR proposal wants it that way.