Interaction is the big one, and I think “costs” is another one.
With interaction, you can both give the player a better reason to care about the proceedings (namely, if this fucks up, it’s YOUR FAULT), and far more intriguingly, you can tell a story without anyone even noticing by way of player race/gender/personality. I’ve written small games where the player could be white, black, brown, whatever, and had that actually alter the story in some ways, most small, some gigantic, but the players won’t know that until they play again with a different race. This can be lead to all sorts of incredible opportunities for education and plot magic. It doesn’t even have to be race: perhaps let the player try the whole game blind, or missing an arm, and see how that alters it all. It’s like Havenstone mentioned with the other characters. How will the mysterious assassin fit into the player’s story if they’re a good person? What about bad? PLAY TO FIND OUT.
Costs is self explanatory. We pay the same amount for scenes set in a small coffee shop as we do scenes about giant space stations being assaulted by elder gods or whatever. This means the range in content can be 1000000000% greater, even within a single game. I kind of long for someone to make a game where all the endings are so vastly different in this way. It would be so much fun. Open door number one to get married and have eight kids and a storybook family. Open door number two to have ruthless corporations destroy your life.
Weaknesses are obv visual things but that’s been mentioned. The only other thing I can think of though is that oftentimes the gamey nature of things can prevent the player from ever connecting with the world or its characters, instead just focusing on the choices, trying to engineer the happy ending they want without ever really taking time to enjoy the words on the page. I know I’m guilty of that kind of thing in a lot of these games, mostly because much of the time, once you get about a chapter or two in, you can basically tell exactly what’s going to happen. This is probably a result of authors trying to streamline their divergent trees tooooooo much, such that there really isn’t any true split in the narrative, instead replacing it with altered dialogue or scene description that, while nice, still doesn’t really change the plot’s direction in any way. It’s like those games that ask the player if they’re evil or good and then have the evil players do the good scenes anyway, just assuring them that “it’s just part of their evil plan” and perhaps letting them kick a puppy for good measure. That’s lame-o! I wish people wouldn’t be so scared of writing distinct trees. Yes it’s more work and many players will never get there, but it’s the principle of the thing.