You're overthinking the issue.
Today's games audience is simply too impatient and/or dumb to play adventure games. That, and the Internet - it's too easy to look something up if you're stuck. 30 years ago, it wasn't so simple. Kids had no money for hint lines and hint books were expensive, so you had to rely on word of mouth from your mates who also played adventure games.
People don't talk about this very often, but at least in my experience playing adventure games in the 90s was very much a social experience. People would get together and just put their heads together for any given game - I did it a lot with all the old Sierra adventures and many of the earlier Lucasarts ones. It was a lot of fun because people would come up with different angles for shit. It's a mistake to think that everyone played these games in aspie fashion (i.e. using everything on everything until something works).
Being able to instantly look something up if you're stuck is, to my mind, a big reason why these games aren't as successful anymore. I've always defended an in-game hint system that's well thought out and progressive such as the one in Under a Killing Moon.
In any case, in the true heyday of adventure games, they were being written and made by some truly brilliant people and pushed a lot of technological barriers. This just doesn't happen anymore. While I don't think adventure games will ever truly die, they'll never come close to the level of mainstream appreciation they once enjoyed. And that's fine.
this is far closer to the truth.
its not the adventure games that died, its that modern day audience for games is completely different
1. modern gamers have the attention span of a toddler. they cant be bothered to be stuck for minutes, let alone hours. they will just play a different game on steam. or look in walkthrough and start following the walkthrough. therefore, devs need to massage their clits constantly, telling how great they are with every click they were SUPPOSED TO do.
2. stemming from #1, modern audience pretends to 'value their time' when it's simply an excuse to not confront and solve problems. they don't like to engage in problem solving or logical thinking, unless it's a game explicitly marketed on difficulty or some puzzles (ie, dark souls or portal). adventure games were revered by a lot of programmers because solving a puzzle youre stuck on relates very well to finally finding an issue you've been debugging for a week trying to resolve. because its so easy to get hints now, people would rather look/watch hints, than actually think for themselves. its an equivalent of looking up an answer to your super hard physics problem online without solving it yourself. it's cheating yourself, really and just says that you don't want to actually solve problems.
3. modern gamers like to cherry-pick what they want to do in a game and not do other stuff they dont like in a game. hence why sandboxes are popular. can't really do that in adventure games, and often the dichotomy of puzzle preventing people who play for the story to progress can cause an issue here, ie 'we are forced to do what we don't like to progress to see what happens next'. and they don''t like puzzle solving because of #2
4. there is no instant gratification in classic adventure games by definition. there is no levelup, there is no rise in power, the reward you get for finally solving a pesky puzzle is some (or in many cases, minimal) story progression. again, this ties with point #3.
Ron Gilbert said it well in his blog posts on Thimbleweed Park:
We're not building a modern adventure game with all the rough edges sanded away and a safety net, ready to catch even the smallest misstep or endless rewarding of the player for the completion of mundane tasks. I know a lot of modern players want to constantly be told how great they are and how amazing they're doing. This is not one of those games. Success is rewarded with the greatest reward of all: New art. Hints are given through well crafted dialog and feel like a natural part of the story. Players are introduced to the game by a slow escalation of puzzle difficulty and a well focused story.
you can pretend all you want this modern gamer mentality isn't the issue here, but it is. an attitude of 'how can I get a game to blow me for these 30 minutes I have while I choke on popcorn' is largely incompatible with puzzle-based adventure games. they have to be telltale interactive movies for these modern gamers play 'just for the story'