You're hitting the phonological analogue of Moravec's law: the "ough" mess is precisely the kind of thing that can't easily be simplified in a way that works across English dialects. It hits a wide swath of basic vocabulary that originally had a small range of slightly awkward pronunciations that diverged in descendant English. Different dialects don't split those pronunciations the same way.

The real low-hanging fruit is getting the British to give up on those spellings that follow a dead branch of French ;-)