For me, you have to breakdown open world games in to open world story games and truely open world games. By open world story games I am talking about things like Breath of the Wild, Assassins Creed, Fallout, Horizon Zero Dawn etc. Where they are open world but the open world-ness is limited to the route you take to get somewhere but they are still linear in the sense that you have to get to a checkpoint at a certain location which will move the story along. Take Fallout 4 for example, you could wander around the wasteland for hours but to progress the story you have to pick a home in one of a few certain locations, you have to visit Diamond city etc. Horizon Zero Dawn is another example, in the beginning you're limited to your little area of map and the only way to be able to get access to the whole map, the 'open' world is complete the story by going from mission at place a, to mission at place b etc. I think a lot of these fall in the time played = content when it doesn't. These type of games often appeal to me but ultimately never live up to the hype simply because of how fast they become repeatative.
On the other hand what I consider more true open world games I do love. Now I'm thinking about it these are all survival games - I have and do play a lot of Minecraft simply because of the freedom it offers you. Though I do also include other survival games like 7 days to die here too. I presume The Forest and Raft are similar too but I haven't played them to know specifics. Where do you want to live? well wander the map and pick anywhere you feel like. What do you want to live in? A small house? A massive castle? an underwater base? a flying base? How do you want to protect your base - a simple fence perimeter? a giant hole? traps? a bridge? a button or code activated door? a drawbridge over lava? What food do you want to live on? Grow and harvest crops manually, breed animals manually or do you want to more extreme and build complex contraptions that automatically breed animals, kill them and cook the meat? Or do you want to take a break from the survival aspect? I've built all sorts of random things over the years - water slides, whole theme parks with rollercoasters, quiz shows. Simply because you can build whatever you want, whatever your imagination lets you.
As for linear games - I do also love these. I see them as something similar to a TV series (I would say film but most linear games are longer than the typical 2 hour film). They're interactive unlike (almost all) TV shows but they are still a scripted story, designed to take you on a journey, for you to uncover things, find things out, experience the plot twists etc. Yes there's terrible ones out there as there are terrible TV shows but the good ones are so damn good - The Last of Us, Half Life, Bioshock, Deus Ex (to only name a few).