I have been reading this very thread just today as well, and have been thinking about it a lot.
Here is my take.
First of all, it is perfectly within Blizzard's power to do it. Whether people like that or not is a different matter altogether.
However, the only group that should "feel" cheated is the same group who, thanks to the early exploits or early lucky drops (yes, that is a big part of it, like it or not), were able to get slightly ahead of the curve.
If, and this is a big IF, Blizzard just left everything untouched and just nerfed Inferno damage levels all over the board, that would not have changed the power game. Meaning that those who farmed Act3-4 for whatever reason (and yes, that includes people who just exploited goblins and chest positions and spawns) and already got a good enough gear thanks to that methods (i.e. avoiding fights at any costs because they did not have the gear to fight the mobs there), could continue to gain insane amounts of wealth and stay ahead of the curve for long enough time to mass large amounts of sum by the time the majority of the dedicated players get to farm Act3, for example.
Is that good? I do not believe that goblin farmers and botters should lead the Diablo 3's market forever just because things got unchanged. So yes, while it is sad that barrels do not drop legendaries anymore, it is no more sad that there are people out there who got where they are right now due to barrel kills. In a game that is about killing mobs.