Wouldn't increasing the Level of the Elite Four make it much more difficult for the children who play Pokemon too? It can't be forgotten that little kids also play Pokemon. If the Elite Four was too difficult for little kids, then they wouldn't be able to beat it as easily as we could, and they wouldn't want to purchase future games. Don't get me wrong, I would love a much stronger Elite Four. But that doesn't mean I won't buy a game because it's too hard unlike a child would. Producers (Gamefreak/Nintendo) would probably favor them more than teens and adults who prefer more of a challenge.
I would prefer the option of rebattling a new Elite Four with stronger Pokemon after beating them the first time, similar to FR/LG. Then everyone wins :)