>>120119937I'd say that, while commercial games can indeed strike the same tone, ultimately often fail due to attempting to push a plot forward which is not designed with said tones in mind.
An interaction with a character people might find endearing, for example, might ultimately fall flat and is rendered "unnecessary" in the grand scheme of the plot, and thus, people don't necessarily attach themselves as well to them due to being connected to said main plot far more than this seemingly random character.
In addition to that, said character might be barely developed and shows little reason for the player to actively talk and engage in actions with them.
Of course, this is not always the case, but I believe that this lack of in-depth development and reasoning for the player to become acquainted with the characters results in them not attaching to the game on a personal level, treating it like a typical video game with simple objectives.
However, games such as Undertale (which I will use as an example here, despite your claim that it wasn't a very captivating topic to you) actively encourage and reward the player for investing effort into talking to the various characters and befriending them, which is why so many people enjoy them.
Talking to the brothers unveils interesting story tidbits. Sparing the mother results in a heartrending farewell and an unexpected reunion. Struggling with the eager friend and their urge to kill you eventually becomes the foundation of your friendship.
I've yet to play LISA, so I wouldn't be able to provide you with explanations and theories as to why people enjoyed it as much as they did, but I'd be inclined to believe that its development and interaction with the various characters helps quite a lot with garnering your interest.
Whew, wall of text.