Bioware.
Bethesda, up to Starfield, while dumbing down every game at least made games that were decently fun and highly moddable. Oblivion is my most-hated RPG of all time for the decline it injected into the genre (and for how it killed Elder Scrolls), but overall Bethesda isn't as bad as Bioware. Their formula has had less of an impact on the genre than Bioware's, and their games while dumbed down and flawed are at least focused on gameplay over story, shallow as it may be.
Obsidian isn't a trendsetter but a trend follower. They haven't had much of an influence on RPGs, they merely take influences and do their own - usually mediocre - spin on them. 99% of their games are just meh, and even the good ones are either sequels or clones. For the first half of their existence they were Bioware junior, making sequels and spinoffs of Bioware games (KotoR2, NWN2). Pillars of Eternity is one of the most boring games ever, but it was basically their attempt to do a Baldur's Gate clone. Alpha Protocol might be unique for its setting in the RPG genre, but the gameplay is a straight up clone of the popamole popular at the time. Fallout New Vegas is their best game, but it too is just using a pre-existing engine from Bethesda and repurposing their ideas for the original Fallout 3, good as the game is, there's nothing innovative about it.
Larian have extremely bad writing but at least their games tend to focus on gameplay, and while some gameplay decisions are utterly retarded (pretty much every single mechanic of DOS2) the games tend to be fun to play. Swen really likes Ultima 7 and he takes that game's interactivity as inspiration for his own games, which results in lots of fun shenanigans with using the environment. Flawed as Larian games may be, they're gameplay-first games.
Owlcat and inXile are decent mid-list RPG devs. Their games aren't great, but they're not terrible either. They don't try anything new, but go for solid proven mechanics and just give you a decent 6/10 classic RPG experience. Nothing to hate there, honestly.
But Bioware? Their games have gone down in quality with every new release since BG2, which was their best game. Their style has defined the current generation of RPGs, and has pretty much created the storyfag brand of RPGs.
The focus on romances - we can blame Bioware for that.
Linear level design with 3D environments that are basically 2D, you can't even jump over ankle-high obstacles - that's a Bioware staple.
Encounter design that's primarily just copypasted trash mobs to slog through between story moments - pretty much what all Bioware games after BG2 did.
Quirky writing that wants to make NPCs "unique" and "interesting" by making them gay and retarded - yep, Bioware.
A focus on over-written companions that take up more of the writing budget than any of the NPCs (questgivers, villains etc) - Bioware is to blame for it.
Out of all the big studios that have been active since either the 90s or the 00s, Bioware is the one that has declined the sharpest.
They gave us BG2, which was legitimately great, with good quest and encounter design, and while companions had a personality, the writing wasn't fully focused on them and them alone. That game's mage duels are legendary. Some of the dungeons are top ten dungeons of all time material.
Then they completely declined into formulaic copypasta. Every game since KotoR has the same companion archetypes. Encounter design took a nosedive, everything is trash mobs now. In Mass Effect and Dragon Age, the combat feels tedious rather than fun. And from their own designers, we even get confirmation that encounter design was an afterthought. It's all about the story now, and even more so about the companions. Spending time in your camp talking to everyone and hearing their sob stories. Companions flirting with you unprompted. And now, their most recent game is going to be the ultimate end point of their trajectory: complete faggotry that doesn't appeal to people who actually want to play games.
All the other developers in this list at least still make products you can call games.
Bioware devolved into writing interactive erotic romances with trash mob interludes.
And any RPG nowadays that feels the same, does so because of Bioware's influence.
