and it isn't that much harder to do things like

Why would you opt for something that is harder? Even if it is only "that much"?

What benefits do you get that offset the extra complexity and verbosity?

What would happen if you did:

my $moose_stack = MyApp::MooseStack->new();
$moose_stack->add_item($foo );
my $saved_value = $moose_stack->pop_item;
[download]

And there wasn't an item to pop?