I can tell you in a heartbeat.
EVs, IVs, stat values--they were definitely cool when nobody knew about them, but now that everybody knows about them, competitive battles aren't fun anymore. What's the point of EV training? Wasn't it more fun blindly training on any pokemon you encounter? I personally find that EVs and IVs suck all the fun out of competitive battles, because, well, I think I already said that I don't find it fun to grind on a single type of pokemon. That's abusing EVs--another thing I don't like about it that most pokemon have absurd stat values because of them. I would do anything for Gamefreak to decide to drop EVs, or better, somehow find a way to hide the fact EVs are still in the game, so nobody would notice--I don't know how though.
Soo...having ways to customize your pokemon and make it more unique from others of its species is a bad thing? I don't mind any of that stuff even though I've fallen out of the competitive scene. It's only natural for a player to maximize their pokemon's potential in a game that encourages competition between players. :P
The only real problem I see is that it alienates the more casual players and the more...elitist of competitive battlers will harass them for it. I feel this problem can be solved if NPCs in the future games intrinsically explained EVs and IVs to the player. The games don't have to get all technical like, "Hey player, did you know that if you kill a lot of Zubats, you'll get a +1 EV to your pokemon's speed, and that if you kill 252 of them, your pokemon's speed will be 63 points higher than it would be otherwise?"...something simple like, "Hey player. Did you know that by killing a lot of pokemon wiht high speed, your pokemon will start growing in speed more quickly? It's true!" would easily suffice.