The problem is that most of the ES/Fallout Sequels tend to take places hundreds of years after the previous one so most of those characters wouldn't be alive. Usually, there's a throwback to something that happened in an earlier ES/Fallout game whether it's in a book, an item or some kind "easter egg" but it's usually there. I get what you're saying but because of how the game is set up, it's really difficult to implement something like that.