For one, it's a Western game, so traveling the open plans and wilderness is part of the appeal, and a core part of the game. It's part of the Wild West fantasy
Two, the world was lively and well spaced out. Seeing a town on the horizon, seeing a pack of wolves roaming, encounter other travelers or cowboys around the campfire.
If anything, RDR is one of the gold standards for how to do an open world that's enjoyable to explore and travel across IMO
Witcher 3 is another.
See i disagree with both statements.
Ghost Recon's idea of "dropped behind enemy lines" is, as i said, sold much more by the fact that the world is one and interconnected, instead of separate spots on a map, so it is seeling me the idea ( i guess like trotting around is selling you on the western fantasy).
Second, i don't think things are spaced out well at all in RDR.
Everything is cramped together, you can't walk too steps without hearing a gunshot, be attacked by a puma, or see someone run around in a horse.. so much for the "lost in the wild" feeling.
It suffers so much from the "mini-golf" thing i mentioned earlier, but that's true for all R* games, and their obsession for cramming everything with content (a problem GR also shares, though less heavy, due to how more spaced out things are).
when i walked around in RDR; as cool looking as it was, i didn't feel like i was in a world, but like in a WestWorld sort of park, where every corner i turned, 2omesthing was to catch my eye, lest my ADHD had my shut it down in boredom.
Unfortunately all open world designers out there seem to take R*'s design as gospel, replicating all their trappings verbatim.
Incidentally, as much as i love R*, i don't think many of their design choices are all that elegant in the end, despite pushing the envelope on a technical level, and having an obsession of detail that does give their worlds an extra edge, when it comes to being lively.
Witcher is a different beast, it's also filled with stuff, some great, some crap, but the map aims to represent a much smaller and contained area, and so it doesn't feel as a theme park, and things are allowed to transition more naturally into one another.
Ghost Recon here, isn't a masterclass in world design at all, but i think it falls between the two when it comes to map design.