I blame both Bioware and EA fairly equally.
EA have obviously fucked up the management side of this equation, and lets not even try to pretend that the idea of using Frostbite - an engine Bioware knew didn't work that well for RPGs - for an RPG, didn't come from EA trying to push its proprietary engine. Had they the option to use the Unreal engine from the prior games and just expand on it again, things would have worked better. EA, ironically, obviously provided too little oversight to the project if it had two teams virtually going to war over it. That's bad management. They needed someone better in that role, clearer instructions on what each team was doing, and firmer enforcement of that. EA probably was also the one that wanted a new Mass Effect, especially given this Bioware is a different support studio, rather than the main "We are Mass Effect" studio.
Bioware, however, is not innocent. EA likely did want to go after the Open World Market, as shown by a lot of their recent games [Though notably not all], however I think its important to note that developers are humans and gamers as well, not just robots that pump out finished products, and this Bioware is obviously far less disciplined than the Bioware that made ME1, or Baldur's Gate. A big part of these projects is deciding which dreams get cut, and keeping everything in scope. Get a focused vision, build it, then iterate on it to improve it and make it more fun. Bioware... Didn't have a clear vision from the start. They were likely just as guilty as EA of going "Oh hey, did you see TW3? And no Man's Sky/Elite Dangerous/Dwarf Fortress/Minecraft? Great idea, but sucked with execution. Imagine if we could make, like, the whole Andromeda Galaxy for people to play in, and they could go anywhere and do whatever they wanted. Wouldn't that be awesome? Sure, maybe we can't make the whole galaxy, but what about huge open planets that really builds on that thing from ME1 where you explored the empty planets, but made far better? And better combat than the previous game, and more RPG elements, and more loot, and an epic story and...". Dreams. Feature Creep. Bloat. Rather than defining what they wanted to make very clearly at the beginning and working towards that, they had some vague idea of what might sound cool and be fun so maybe we try this and try to get everything working brilliantly. I was thinking on writing a huge exposition of what was wrong with the game, but it ain't worth the effort. Put simply, this Bioware team, alongside the ME3 team, lack the experience and discipline of the old studios, and have a lack of clear studio culture. They just kinda jumble stuff together that sounds kinda cool on paper, and hope it turns out alright. The old Bioware had obvious cultures to their teams, and the Dragon Age team to some extent still maintains this. A clear image of the types of games they want to make, and do make. Its what we identify a "Bioware" game as. There is nothing to attribute to new ME Bioware except excessive ambition without the discipline to pull it off.
So, overall, both have a foot in this mess. EA is doubtless the mastermind behind it all, failing to actually plan effectively for anything, and trying to shoehorn in their own brand of BS where it doesn't belong, but Bioware just aren't up to the task of making large games - either of the ME studios. Their leads are as incompetent as EAs, and it shows in the games they're making.
