The departure of Luis Barriga surprised me, because so far I have not seen his name mentioned as one of the culprits and I don't think he was seen in any of the pictures, either.
It's a dramatic development for D4 to lose the game director at this point in time, that's for sure. Whether it is ultimately good or bad for the game, I can't say. In some ways, I feel that Luis was on the right track, especially regarding art. But in other ways, it still looked too much like D3 for my taste, especially the cartoony animations. Also the updates on system design like skill trees looked like they do not know what they are aiming for and are just going through many design iterations without making real progress. And then there's the open world events that seem tacked on and are not really needed. So maybe new leadership will lead to some improvements.
The best case scenario appears to be if VV would take over D4. I have to say that D2R looks amazing and the people involved in it certainly appear to "get" Diablo like the Irvine Blizzard team never did.