Yes the open world thing requires so many assets and details. I've seen bland projects that need another 4 years of world building. But the devs think being indie will let them put out a bland world. Or even pixel art it all and call it retro.

There is one group I'm watching that is doing it well. But they did a really smart thing. They limited the size. It's a game about seizin and controlling a neighborhood block. It's larger than a single block but not large at all. They built it basically of gray art, then started the task of detailing it all. The team member I talked with said it was well over a year to build the game, but it might take 2 more to detail out the world and truly bring it to life. That's if they get more help and can raise the funding. I played a bit of the gray art game - It was fun , but really took a dev-player to be able to look past all the gray art.