The old brick separator seemed indestructible, and would separate all bricks that I had without fail. This orange thing is dinky and flimsy compared to the others.
So, I ask, why did LEGO think that this is better? Is the only reason the wedge?
The new brick separator is smaller, therefore uses less plastic and is cheaper to mass produce, it also means it can fit better into tighter spaces.
It has a pusher to remove Technic pins and a chiselled edge to pry off tiles, there is a middle hole in the two female stud connections which allows you to remove 1X2 'jumper tiles'.
The additional Technic axle connection gives you a little bit more freedom to incorporate the part into other LEGO creations.
Brick Wiki has no reference for this, but it also seems like a sensible decision consideration:
A new style of brick separator was introduced by LEGO in late 2011. To the satisfaction of many AFOL's, the new style comes in orange. (Many AFOL's had wished for brick separators to be made in orange for years, so that they could be spotted easily when needed.)
My guess would be that they wanted to include one in more sets; so they made a smaller (cheaper) version and took the opportunity to add functionalities, such as the technic axle remover or the flat end for removing tiles easily. If I'm not mistaken, this version works on jumper plates too; which wasn't the case with the old one.