This is a pretty bizarre effect when you think about it, but there are certainly decks in Commander that have a lot of power 5 or greater creatures. If they all suddenly gained flying that could become quite a problem.
Then again, where would you slot this into a Commander deck when you could just make those creatures have trample or even un-blockable instead? Actually, there are some Mayael the Anima decks out there that do run Gustrider Exuberant! Also, there are a few casual decks that have made use it. But Mayael EDH decks seem like the best home for this guy to me.
In any case, its effect is a fascinating thing to put on a common creature – that’s for sure!