got to watching the henry stickmin franchise again, I realised how true this still holds. think about your favorite game franchises of all time; Mario, Mortal Kombat, Doom, even plot-heavy franchises like metal gear or COD started relatively simple. simple mechanics, simple stories, a simple gameloop.
This lowers the cost of development and in turn the cost to the player to try something new. If players see something they like, they'll be more likely to spend more on the sequel, and in the meantime, word of mouth advertising can get the game going.
rather than spending literal billions trying to get a new ip off the ground, studios can spend significantly less money trying new concepts and introduce more complexity as time goes on, rather than trying to hit the ground running.
Because everything is work shopped to death to appeal to everyone. There is no more "this is cool." It becomes well "this is good but..." and everyone is nitpicking things to appeal to just one more demographic. So you can't just make a movie about soldiers in the trench trying to survive you need to shoehorn in a romance plot. But you can't just have one woman, you need two to pass the bechdal test. Then there is something else that needs to be changed because someone found it icky. Before you know it appeals to no one.