Yup, agree with that. Saying that, I have around 40 mods pre-loaded into my game currently. It's so immersive and involving. I'm not into all the cheating or God mode stuff, but more the surroundings, texture improvements and general updates to the game world. It's brilliant. Really enjoying it yet truth be told it's not that impressive, from a "next gen" perspective.
I think it's because it's map isn't too large and is very dense with places - I only wish their were more missions or side missions that used these locations - seems a waste that some areas clearly had a lot of effort put into them but they weren't really very important.
With Witcher and MGSV there's lots of travelling, the worlds are pretty big and there's lots there, but it's quite spread - I went straight from playing Fallout to MGSV and instantly not having quick travel, having to wait for helicopters etc was a bit frustrating although I guess ultimately more real.
I guess that's what Fallout can get away with more than Witcher or MGSV, it makes no real attempt to be believable, which means it can completely eradicate cumbersome things that would need to be in a 'real' game. You can carry masses of items, you can fast travel anywhere instantly, you can get great guns from pretty much the get go, few cutscenes; more play time.
I think it's something developers will have to look at going forward, the recipe up till now has just been to make these open world RPG games bigger and bigger, but that's not always better.
EDIT: Far Cry 4 was the worst for me in terms of the world being big for the sake of being big - hundreds of discoverable locations that don't matter at all and are never used in the relatively short campaign. All the landscape looked the same, just one huge jungle, and having to travel all the time on the buzzard.