I don't know how you can look at Fallout 4, then compare it to FO1, 2, New Vegas and even FO3, and not conclude that Bethesda did anything but target a whole new audience with 4. Fallout 3 was a reboot designed to get the fans of the original games back into the series, and while we can argue that it came off as a weak effort, at least it was clear that they did make an effort. New Vegas was a much stronger effort to connect to the original games, and again, at least Bethesda made an effort, even if they did farm out development to Obsidian.
With Fallout 4, they threw any pretense at appealing to the established fans out the window, and decided to use the Fallout name to make a lazy cash grab designed by the marketing gurus to appeal to the widest audience possible.