I have to disagree on this one. Going back to Baldur's Gate 1, there were more than a few quest lines that consisted of simply "kill this npc, collect this wolf skin", with virtually no other in-depth content to supplement it. Even the context for some of the moral decisions were pretty bland.
I'm not saying those quest types are the most interesting and I acknowledge that DA:I has even more than most, but BG1 at least was not just about rich and interesting side quests (imo). I will admit that Tales of the Sword Coast was a bit better in that regard, though.
Well that's why I also said that the CRPGs were arguably the first step in a reduction of the kinds of detail in the adventure itself. D&D had no budget constraints or whatever so the DM was free to make the worlds and characters as interesting and cool as possible. That meant you could be doing a "fetch quest" and suddenly 3 gods came in. At least in the D&D campaign I played things were never normal, you ended up stuck on a ship with a bunch of Tanaari who then suddenly fell into a conflict with Baatezu and the opportunity to escape arises, but you have to fight both sides who are fighting each other, and yet you have to leave one behind, or whatever.
Also in BG2 there are basically just 8-9 lengthy story type quests, Harper, Ranger, Paladin, Fighter, Druid (which was a little more boring, sure), Mage, with tons of interesting highly detailed things like the silence of the lambs guy in the one district, the thief guild.
See but take BG1 also, coming across Drizzt, that's cool, cause he's such a major character. Or going and doing the Gnoll Stronghold with the Edwin and Minsc, both of which are after Dynaheir for different reasons, and you go over like at least a couple zones to get there.
Finally, at least once upon a time, what are now called "fetch quests" were considered somewhat cool. The idea of going out to fight gnolls was interesting because gnolls were new and unique as was questing and being a paladin, at least in video games. It's long since past that point, though.
I would say it was WoW as much as anything that spawned the generation of thousands upon thousands of quests. Cataclysm had literally 3000 quests! Skyrim is somewhat similar, although many of those were in at least a somewhat detailed manner.
A company like Bioware doesn't have the resources really to make that kind of volume, but also, why would they? It's just a form at this point, an expectation that there be lots of grinding. There's a massive disparity there but it shouldn't really come as a surprise at this point.