Since it's mathematically impossible. I'd love to see GF even try, lmao.
How does this make the breeders who hate any players who don't do things their way feel? No matter how many years you spend breeding, all that will go to waste as a shiny Lucario with max IV's in all the necessary stats annihilates your team utterly. At least you guys got to bond with your pokemon though, right? Even if they do suck, that's all that matters in the end, right?
True RNG can't be banned totally, but it can be ruled out effectively. If they really tried, I'm sure they could come up with sequences that can't be cracked the simplistic methods sites like smogon use.
To do this though, at least effectively, they'd need a professional cryptographer. This reason alone pretty much tells us GF won't try anything to limit RNG abuse. This also of course assumes hacking will be completely impossible, which is a terribly naive notion in my opinion.
Actually, despite it not being intended, and definitely not as a countermeasure to RNGing, Black2/White2's little bug where the first Egg picked up from the Day Care upon booting a file being almost entirely fixed effectively made RNGing impossible for Eggs. For those that think this was evidence that GameFreak is trying to stop RNG abuse, think again- they removed C-Gear Seeds from Black/White and made RNGing Entralink Pokemon a ton easier. If they were really so anti-RNG, they definitely would not have done that.
In any case, if the breeding bug from Black2/White2 remains in XY, it will be extremely difficult if not outright impossible to RNG Eggs.