I think this is a good idea. Dunno why you are all making a fuss of this, I think you should all just take a step back and think rationally rather than just assume this is "OP" which is not.
The chances of you getting a shiny with good IVs, and have it have the right ability and nature is almost astronomical. So why not help with that a little and give a random try at the nature only?
Let's be real here how many people actually try to hunt specifically for pvp shinies? Nobody. How many people do you see with epic shinies? Next to non existent.
If the game was as easy to get battle ready shinies in cartridges, then you better believe I'd have a problem with this but it really is night and day when you compare so I don't see the issue.
+1