Originally Posted by
xskarma
Well the effect of this is that it's pretty much impossible to get full BiS, with everything you hope to have on it. On the flipside, the advantage is going to be that you have a better shot at getting a functional piece, even if it's not the ideal piece yet.
Raids will likely be tuned around getting the vanilla version of the gear, so every time you get a piece with soemthing extra it's going to be THAT much better. It also means that instead of having no reason whatsoever to run boss X anymore cause he drops nothing useful for you, you'll still be able to get a better piece from a boss.
The cynics will say this is meant to drag out the effective lifespan of a raid tier so Blizz has less work to do, the more optimistic view is that Blizz have found a way to keep playing the game interesting, even if initial progression is done.