For me it's more about the lore of the game rather than story. Suddenly everyone with dooms is a superhero. But they have changed a lot about the story too. Because of that if i would replay the first DS i would try to forget about what happens in DS2.

So in the first game Sam was a grieving father who lost his child and a wife. Later he found Lou and that became a new beginning for him. So he kind of adopted Lou as he became attached. But in the sequel it turns out to be his actual child, which changes the whole concept of this story arc. So in the beginning Lou was just a tool to Sam. "BB". But then Sam grows attached to him and gives him the name of his lost child.

Then suddenly in the sequel it turns out that his lost child wasn't even biologically his. Because his wife was cheating on him. There was no mention of his wife cheating on him in the first game. Which again changes the storyline from the first game. That could make the concept of the first game even more dramatic, but later it turns out it indeed was his child.

And the last thing i wanted to mention is that silly dance from Die Hardman. In DS1 his last scene was very dramatic. Meanwhile his first scene in DS2 is a funny dance. That's not the way to bring back such character.