It's still Fallout.
There may be differences, but, by owning the license, Bethesda has the creative license to make any changes they want while still keeping core elements of the original or preceding titles.
When Disney bought the rights to Star Wars, they made some decisions about what is and isn't canon in the lore ... and, because they own the rights, they can continue to make changes, regardless of how much you, or I, or anyone else likes those changes.
Of course, ownership of a license or product while allowing for the creative license to make changes also runs the risk of alienating and disenfranchising fans of the product. Still, that's Bethesda's call to make, and whatever changes, additions, subtractions, twists and or turns they take with the overall Fallout Universe is all theirs to make, and continue to make and adjust according their creative vision.
If you don't like it, oh well.
Mods are supported.
Take a deep breath, wait a minute, and then make a mod that takes out everything that offends your ever so refined sensibilities about what you think Fallout should be.