Question about creating objects using Moose::Meta::Class

Greetings.  I was leafing through the Moose documentation the other day 
when I stumbled across Moose::Meta::Class.  If I understand correctly, 
one of the things I can do with this module is create metaclasses, then 
use those to create new objects.  However, when I do so, the BUILD subs 
don't seem to be called in the same way as when I create objects from 
"traditional" Moose classes:

Consider this bogus example:

---

#! perl

use strict;
use warnings;

package My::Class;
use Moose;

sub BUILD { print "BUILD for My::Class\n"; }

package My::SubClass;

use Moose;
extends 'My::Class';
sub BUILD { print "BUILD for My::SubClass\n"; }

package main;

use Moose::Meta::Class;

my $mc = Moose::Meta::Class->create( 'My::MetaSubClass',
    superclasses => [ 'My::Class' ],
    methods => {
        BUILD   => sub { print "BUILD for My::MetaSubClass\n"; },
    },
);

print "Creating a new object from the metaclass\n";
my $obj_from_metaclass = $mc->new_object();
print "Creation complete\n";

print "\nCreating a new object from the My::SubClass\n";
my $obj_from_subclass = My::SubClass->new();
print "Creation complete\n";

---

When I run this, I get the following output:

---

Creating a new object from the metaclass
Creation complete

Creating a new object from the My::SubClass
BUILD for My::Class
BUILD for My::SubClass
Creation complete


---

I would have expected the BUILD subs for My::Class and My::MetaSubClass 
to have been called when I called $mc->new_object().  Of course, I can 
do this manually by using $obj_from_metaclass->BUILDALL().

Is my expectation of the BUILD subs being run unfounded?  Or, more 
likely, am I completely misunderstanding the intent of 
Moose::Meta::Class in the first place?

Thanks!
Tom