One of the Obsidian members revealed the reason, and it’s somewhat painful!
Fallout: New Vegas was developed by Obsidian (who might be doing a new Fallout game – we wrote about it yesterday here), so they know their game the most. Scott Everts, the team’s technical designer told the following to PCGamesN:
„[Fallout: New Vegas] would have been a lot different if it was PC only. We had a lot of plans early on. Like, ‘Here’s where the water is stored, here’s where the farms are, here’s where the government is centralized.’ We had it all planned out – it wasn’t just a bunch of random stuff. We could have gone further with that [without consoles]. We had to simplify, so we had less stuff that would bog down the game engine. The game would have had fewer performance issues. We did break it up a bit, but from my point of view it was a performance-related game, and we had to fix things.”
In short, Fallout: New Vegas was held back from its full potential because of the consoles! Unfortunately, there’s no chance of a new Fallout game being PC-exclusive: Fallout 4 sold 12 million copies on PlayStation 4 and Xbox One, while the PC got „only” 1.5 million on the table…