After witnessing a considerable amount of English natives asking those drunk, swum and sung questions around the discussions here on Duolingo, I must say you guys started to make me feel mildly discouraged at first. Don't get me wrong, I just still remember the painful days of having to deal with those irregular-verb tables for English class. But now I have a feeling it's actually about English "developing" as a language.
While it's always irrefutably advisable to use the gramatically correct forms, I wouldn't be surprised if some past participles like those start falling out of use in the future.
Just think about it: although we would probably all agree that there are some considerably better methods of mastering irregular verbs, it still means simpler irregular-verb tables for future humankind! Yabadabadoo!
But if it ever happens, we should give English at least a century (or few) to do its thing :)