It's not necessarily a problem with personel rotation. Look at id Software. There's almost no one from the original crew on board and they're still making great FPS games.
Trying to compare the story line from DOOM to that of an in depth RPG is a really big stretch. Doom has some fun shooting mechanics, for for a person like me, that holds very little water without an amazing world to back it up. What Bioware lost have been most of its creative talents. Take a look at the career of Drew Karpyshyn and you will see what I mean. Even outside of loosing their best creative minds that influenced their amazing worlds and in depth lore, their game play has also been dramatically reduced. Here is a short timeline to show what I mean
Drew Karpyshyn, lead writer on Mass Effect and Anthem, left in 2012, and then again in 2018
David Gaider, lead writer of Dragon Age series, left in 2016
Chris Schlerf, writer on Mass Effect: Andromeda, left in 2016
Ian Frazier, Lead Designer of Mass Effect: Andromeda, shifted from BioWare to EA Motive in 2017
Aaron Flynn, ex-General Manager, left in July 2017, shortly after Mass Effect: Andromeda's launch and after 17 years with BioWare (replaced by Casey Hudson, who previously had left in 2014)
Mike Laidlaw, ex-Dragon Age creative director, left in October 2017 after 14 years with BioWare
James Ohlen, lead designer on Baldur's Gate, Star Wars Knights of the Old Republic, and Dragon Age: Origins, leaves BioWare in July 2018 after 22 years
Ben Irving, lead producer on Anthem, left August 2019 after 8 years with the company
They lost the talent that made them what they are because of corporate greed and lack of creative freedoms.