I'm not sure if it is entirely the fault of 3D graphics, but what else can it be?
First point, IWD1&2 great RPG is a wide exaggeration, very fun at best. PST could be great on some aspects but is crap on other, released nowadays with only a graphic upgrade, it would get a huge bash, and nope the cool Beamdog refresh isn't like a new release and is far to have sold well enough to sustain such budget level.
It's clearly not just 3D, there's been modern non 3D ambitious RPG with only some limited 3D aspects, and they shown no lead in amount of content or quality.
For graphics, it's not 3D it's just graphics detail level. If a few games, those from Infinity Engine and none else throw a confusion on that, they won't match a direct comparison with modern games. It's more than 3D games of their time are now all totally ugly when it's not that obvious for those non 3D games.
Other reasons:
- Class systems, sorry but D&D2 is D&D2. Objectively Fallout 1&2 skills system is weak, if it wasn't the perks, that was defined for most in few days, just a miracle here, nothing repeatable. Might&Magic class system, weak for today standards. I don't remind it was much better for other big series of the past, Ultima, Wizardry, Dungeon Master, many more.
- Writing level, a modern AAA RPG couldn't be released with Ultima 7 writing for example. In my opinion there's a screw up of modern industry here, but the point is here. In this past, a few writers, and most not really pro, it's now many pro writers, a full leader with leading and management like there wasn't before.
- Companions writing, for RPG having it.
- More writing not done to complete graphics low details.
- Character customization.
- More work on showing equipment on characters/NPC/Enemies.
- More advanced UI design without to mention problems of consoles and touch stuff compatibility or potential compatibility.
- A voice acting a lot more pro, even if it seems there's a recent changed last years to push to lower costs and management difficulties.
- A lot more voice acting.
- Much more work and much better work on sounds.
- Much more work and much better work on music, the old music loops repeated ad nausea was such a shame.
- More work on matching new standards, as a big (often boredom) amount of crafting.
- More focus on replay diversity, with more random variations aspects.
- Support of more zoom in/out looking good and performing well at all range.
- And then all the topics brought by 3D but hardly skip-able in a modern context for a game using iso mainly. Light sources design, animations level, realism level, special effect, many more.
- Since Skyrim, RPG are pushed to bigger sizes.
- Bigger projects mean much harder to manage, and even harder to manage a quality and a coherency, even more time than from a size increase, like 10 time bigger team is 20 time higher cost.
- Bigger projects also mean more time for each release and harder to manage, for sales, fame, competition, obsolete aspect.
- Younger dev are just less competent and smart, well perhaps our generations was more competent and smarter, I'd love believe it, I have doubts on it.
- Nowadays dev developing isn't attracting as smart people, mmm, then why?
- Mobiles and free internet, mmm could be, I saw a cool series on that topic on Netflix, that's intriguing and questioning.
There's two points most players don't realize:
- They believe what they would want would sell a lot like they seem have done in past. But nope. The point is BG2 sells wouldn't sustain well enough a BG2 project done today.
- No matter how it requires sells, and sells face current context and current competition level. Competition is dragging on the height, but sells is the only final criteria, not the opinion of some players.