I agree that it's wrong to harass a writer for an update when they have made it clear that they have some sort of crisis going on or that the story is completed as written. Or even that they have lost interest in finishing a story.
I don't really have a problem with people suggesting that a one shot be extended into a chaptered story. Several of my best stories started out as one shots. If I think a story might work as more than a one shot, I usually mention in my post that I'm not opposed to continuing if there is interest. For me, update requests actually help with my motivation. I think I work more efficiently when I know someone is waiting for an update.
It was reader input that drove me to write a 145,000 word story in 2.5 months. Without those readers, it would probably have remained as a one shot of about 6,500 words. And I would have missed out on an amazing learning experience.
With some writers "oneshot" means "this is it, done, finished, don't ask for more." With others it means "here's an interesting idea/premise, I wonder if it there will be any interest?" I don't get mad at being asked for more unless it is just phrased obnoxiously. I usually give the request serious consideration and see if it sparks a vigorous plot bunny or not. If it does, it goes on the list. (Which is growing almost daily.)