load_classes() ensures everything is hooked together properly. It's a bit of side-effect magic that mst isn't thrilled with, but at least it's (mostly) all in one place. Go talk in #dbix_class@irc.perl.org if you really want to understand more.
My criteria for good software:
Does it work?
Can someone else come in, make a change, and be reasonably certain no bugs were introduced?