I know it's not exactly the same, but Bethesda generated a lot of random content in the past to save time and make their games bigger. These content always felt generic and devoid of interest, most players demanded more handcrafted designs to make sure the feeling of traveling through souless generic places was not present. Although they still have some part of that in the game already, it's something so secondary that doesn't actually affects the experience.
No Man Sky had these kind of complaints and fears as well. You can have a million of endless planets, but they are all probably going to be similar to each other with little things of interests, since they will generate the assets from the same source, there is just so much you can add into the game, without making it feel like it was crafted without any sense. So you will not encounter planets with traps that will cause in you an emotional effect because if they exist they will be placed at random. You will not find portions of the game where you can take cover and solve fights from different approaches because all the content will be random without any coherence or logic behind it.
Remember that quest of the museum of witchcraft? something like that wouldn't be possible in a procedural generated enviroment. Neither stuff like quests, or the whole area outside diamond city with the destroyed buildings and enemies placed in certain parts for a reason, with signs showing you the way the first time to prevent you to get lost, or the carefully placed secrets. Instead you would get the feeling that you are constantly playing the same thing for 1000 time and grow tired of it quickly. If people complained about Skyrim's Draugr tombs, when they weren't even the only kind of dungeon I can't imagine their reaction if all of these were procedurally generated. You wouldn't even get puzzles, and in fallout's case, you can't even get terminals with procedural generated stories and content. Unless it's all related to similar patterns that will repeat themselves over and over, like for example, each time you find a terminal, there are meant to be turrets around. And so on.