Its pretty simple to understand why they did it, its because ranged classes like Mages and Demon Hunters could wear nothing but MF gear while sitting back behind Monks and Barbs who need their best gear to survive and tank.
I think it was a good idea, and not a fan of the change.
Not it wasnt. They also made the game significantly harder while in coop play so chances are most people dont play in groups anyways and if they did, probably not with mf gear on. Theres nothing that says monks and barbs cant wear mf gear.....
It has been one of the dumbest things implemented in an item find game....ever. The game has screamed solo play all along. MF distributed to teammates and game is significantly harder while in coop. I dont think that many people play in groups to begin with, let alone to MF.
I agree with Brainonska511 though. The better idea would be, just give the teammates who dont have mf a bonus to mf without penalizing the players who stacked mf. With that said, there are plenty of experienced D3 players who will tell you they find just as many good items with ZERO mf as they do with 200+ mf.
On another note, nobody plays D3 anymore anyways.