It makes so you don't have to invest in two boxes in order to get the cards, it's really helpful.
Imagine having to go through two or three separate boxes just to get N or R cards.
Except sometimes you need to open that other box anyway if you want to play the deck.
A good example of this is the reprint of Koa'ki Meiru Boulder in Revolution Beginning, when you need to open Gaia Genesis anyway (and therefore get Boulder from Gaia Genesis) if you want to play Koa'ki.
It's better for newer players, but admittedly a bit of a kick in the balls for veterans. Still, I believe it makes the game more accessible and that can only be a good thing.