While it might seem strange to you to consider modding essential, this is one of those games with a large number of players who do. That’s just the reality.

And that's exactly why I treat that view as my opinion and nothing more. There are good arguments for both views so...

When Wasteland 2: Director’s Cut automatically updated onto accounts for people who already owned the game, it simply appeared as a new, separate game.

That's also a good way to deal with it, although wasn't it a lot less "meaty" update in Fallout's case? Giving people easy way to rollback would be the best I think. Hell, not only in this case, but overall keeping two snajpshots back for games with heavy mod support could be a good thing.