One reason that it is a Very Good Thing that it works this way is that it allows you to write things like subclassable factories, where the class of the thing being constructed is determined by the factory subclass.

  package Factory;

  sub makeThing {
    my ($class, @args) = @_;
    my $thingClass = $class->thingClass;
    my $thing = $thingClass->new(@args);
    $class->magicStuff($thing);
    return $thing;
  }

  sub thingClass { 'Thing' }

  sub magicStuff {
    my ($class, $thing) = @_;
    # pretend there's generic magic stuff here
  }
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Now, to change the class of the thing being constructed, you simply subclass the factory class and override one method.

  package SpecialFactory;
  use base qw(Factory);

  sub thingClass { 'SpecialThing' }
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Now, Factory->makeThing gives you a Thing, and SpecialFactory->makeThing gives you a SpecialThing.