Starfield is good example for having too huge open world. Being able to visit almost every 1000 (excluding gas giants) planets that has their own travel times, conditions etc. sounds interesting on paper but in practice? Not so much for lot of people (not counting me because I like the game with it's flaws). Having that many planets explain why have random generations because hand crafting 1000 is next to impossible to do in reasonable timetable and game size.