I think it's a bit of a pick your poison thing really. I'm training an MMA fighter at the moment in Muay Thai, but the guy is competing in MMA and already has quite a side on stance - and seeing as he's comfortable and he moves well out of it, I'd have to be out of my mind to try to take him out of it and get him to stand 'correctly' for my purposes.
So I opt to keep his side on stance and am introducing him to side kicks. Thankfully he has a very strong wrestling game (a rarity in the UK).
Wonderboy did lose to the two best leg kickers he has faced, but neither of them were performances where his legs were really battered by them. His division just doesn't have an Aldo.