If recurring NPCs are usefull or not depends on the story. There are base oriented story line (you have a base and from there you go out and solve mysteries, finish quests and other stuff) or moving forward storylines. DOS1 and DOS2 (at least the Fort Joy part) are moving forward storylines. You started at the beach and moved forward from one region to the next. There weren't many NPC fitting for a recurring role, backtracking would have been probably more annoying than enjoyable. Honestly, Esmeralda for example was never really important, outside of being a trader. Even during the quest she was only a false track, a distraction.
Not sure, if you will have any kind of a base in the other part of DOS2, it could be that you will form a of base for operations with the seekers.