>>714274464Because human beings like familiarity and want to feel like they're part of whatever is happening.
It's literally the monkey-brain looking at a recognized face and feeling like the pack is together.
That, in addition to the idle idol worship that pervades people that want to follow everything certain people do, makes it so there is a legitimate monetary value to bringing on a recognized face that people like. The same thing happens with voice actors, like Keith David or Steve Blum, that have recognizable voices. People will generate online hype and buy games if they really like a person.
Sometimes, though, it is just a way to lose money since the game's director and/or creator will just have an excuse to indulge their own idol worship (looking at you, Kojima) and try to pal around with that one dude from that TV show they like, or unsubtly flirt with a cute girl. Creative feel-goods for the leads of the project can be budgeted for, if the game skimps of gameplay and coding is outsourced to India, after all.
It also makes the video game creator feel like their project is 'legitimate' when some notable rando from Hollywood is able to show up in the credits. That actually matters to some reviewers and for some shareholders, so it has a bit of merit.
