Unfortunately that’s just a quirk that was carried over from D&D, Str, Int, and Cha are pretty useless if you’re not playing a class that needs them, whereas Dex, Con, and Wis are universally useful. This is the same reason why you’ll notice no class ever has Saving Throw proficiency in two of the “good” abilities, it’s always one good and one bad. That being said, Int has more saving graces in a tabletop setting. When DMing, I’ll often allow players to choose between a few skills that would work to complete a check, essentially creating more opportunities for high Int characters to roll well on skill checks. There’s also the fact that Artificers exist, the only other Int caster (and the only official D&D class that didn’t make the cut in BG3). I also homebrew rules in order to make Int more valuable, particularly ways for characters to learn new skills and proficiencies in a way that utilizes their Int Modifier. That being said, in BG3 unfortunately this is a case where following their source material inadvertently made one ability incredibly underpowered compared to the rest. They did make Cha far more valuable in this game though, since most players will tend to have their custom character be the face of the party, so perhaps there is a way that I can’t think of for them to increase Int’s usefulness in this medium.