>>2887373I think it just comes down to spectacle creep, where a long-running series is constantly pressured into ramping up the stakes with each entry.
If the heroine is seen in her underwear in the first chapter, then she has to be seen topless in the second and then completely naked by the third. And once the author runs out of ways to have her become 'more' embarrassed, the series starts to get really rape-y. You can introduce a new character like
>>2887375 implies, but then you have the same pitfall of repeating the same story again and again. In that case it's better to just make an anthology series, and if you're doing that already then you might as well not have a connecting gimmick at all, since it's only limiting what kind of stories you can tell.
Plus, there's also the fact that part of the thrill of ENF stories comes from the risk involved. If there's no risk, then it's just exhibitionism. If a girl is streaking around trying not to be seen naked, there's an implication that something 'bad' might happen to her in the situation that she's caught. If a reader gets four or five chapters in and the author hasn't had her get assaulted or blackmailed or seen by her coworkers, then they realize that the author is bluffing and the heroine is in no real danger. Of course, if she actually gets assaulted, then it stops being an ENF story - so the situation is lose-lose.
