Adventure games in general are a hard sell these days, even for guys like me who worshiped Sierra On-Line and LucasArts developers as gods throughout my formative years.
Speaking only for myself, there are quite a few relevant factors. Possibly the biggest is my puzzle-solving ability, which has come an extremely long way since I was 9, yet I still wish to be stumped while playing. My bar for puzzle difficulty is therefore far higher than it used to be, yet modern adventure game puzzles tend to range from relatively easy to practically nonexistent.
Additionally, the writing, humor, and especially pop culture references rarely measure up to the classics. Let's face it: 90s pop culture was a whole lot cooler than today's, even at the time. The 90s had OJ Simpson, Pogs, MTV, Beavis and Butthead, MST3K, Jurassic Park, Aladdin, Beanie Babies, Tupac Shakur, the Spice Girls, and Pearl Jam, while we have Bernie Madoff, fidget spinners, PewDiePie, Rick and Morty, Keeping Up with the Kardashians, the Emoji Movie, Frozen, minions, Katie Perry, Lady Gaga, and Taylor Swift.
Even setting the substance of the decades aside, creatives in the 80s and 90s seemed to have a certain special something when it came to producing works of imagination, games being no exception. Today, the best that can often be hoped for is to desperately attempt to recapture that lightning in a bottle.
Another factor is politics, particularly identity politics. I don't want a gay and transsexual pride parade marching through my fucking adventure game unless it happens to be an adventure game about a gay and transsexual pride parade. "Inclusive" shoehorning is painfully obvious, cringe-worthy, and off-putting, and no amount of downdoots from Codex socialists will change that fact (or encourage anyone to buy more copies of adventure games that suffer from this affliction, for that matter). By the same token, I genuinely don't want to hear about Mormonism, fiscal conservatism, nationalism, secure borders, freedom of speech, the right to bear arms, or any political platforms associated with right-wing politics, either. It's fine for characters to be gay faggots or redneck doomsday preppers, but if you're virtue-signaling, you know it—and so do I. I want to play a fucking game, not read a moronically "disguised" pamphlet outlining your precious political beliefs, you fucking goofball.