I think All these people are leaving because the company isn't theirs anymore. We all knew it was going to happen eventually, when EA buys out your company they take away your creative freedom and it ends up ruining the company.
I think EA pretty much liquidated BioWare at this point because it isn't really BioWare anymore is it?
It's a tragedy and the modern day cautionary tale for any aspiring game developer.
As I've said elsewhere, BioWare accepted EA's money despite BioWare being one of the most praised RPG developers around(giving them success and sway to refuse EA's offer), so EA is hardly the only one at fault here.
We can blame EA for buying all these companies, but those companies accept the money despite being so well-loved by their customers, so the companies are at fault too. There's a reason "victims" of bribery are charged for the crime too.