You're absolutely right that BW is a gutted shell of it's former self. Drew Karpyshyn was a huge loss during the ME2 cycle I believe. His departure caused ripples that we most prominently saw in ME3 when Casey Hudson and company had to come up with the Star/god child. Then in 2016, BW lost David Gaider who had been on board since 99 who largely wrote Dragon Age. I doubt there's more than a handful of staff leftover from the pre EA times.
Drew was just the tip of the iceberg too. They lost Chris L'Etoile and Brian Kindregan as well...and the people who took their characters over were more superficial.. or just outright ignored parts of them. Drew might've been the mastermind, but those two were on a different level as far as characters go.
Chris L'Etoile was like the unofficial loremaster and wrote the Codex. But also wrote Legion and Thane (among others). Both characters got screwed in ME3. Legion's whole schtick about hating Reaper Code became the complete opposite in the next game. And Thane got a lame ending. It took Citadel to do him justice. I liked all of the underlying spiritual themes both characters went into as well (again, Citadel finally did this part justice. I'll give Me3 credit here).
While Brian Kindregan wrote Jack and Grunt. At first, they might seem like silly "edgy" characters, but they both had this pain factor element.. like a "strength through pain" philosophy. He also created Tuchanka and projected that pain theme on to the whole Krogan race. The Krogan before him were mostly just brutes and resigned at best. Not relishing in pain. With Jack, he took the suffering biotic idea from ME1 (like Kaiden or the random missions where they'd attack you) and did this whole female Wolverine theme.
edit: Oh, Warlord Okeer. Another Kindregan character. This whole angle of conquering the genophage through endurance was lost in ME3. That was the whole point of Grunt.. to start a new strain of Krogan and defy the Genophage by sheer badassery. A more brutal "quality over quantity" solution.
"I acquired the knowledge to create one pure soldier. With that, I will inflict upon the genophage the greatest insult an enemy can suffer: To be ignored."
But once ME3 came, Wrex took the attention again and the message was Genophage, Genophage (which is cool, but it became an either/or situation.. and ME3 lost these interesting middle grounds that thought outside the box). ME3 was downright bizarre in a way, where Shep basically was told to do EVERYTHING Saren wanted to do in the first place: Cure Genophage, ally with Reaper upgraded Geth, merge with machines, etc.. The game pushed a very defeatist message.