This is a good topic, so I’m surprised it didn’t get more - or any - replies. I think it may boil down to ‘What is Wattpad, really?’
One thing it isn’t is a conventional web-based bookstore like Amazon, where readers expect to find only complete works.
Wattpad started as, and for the most part still is, a social writing site for serialized works. It’s a core aspect of it that the works come out chapter by chapter on some schedule, so that readers have a chance to anticipate and comment on each new chapter as it appears, and the writer has a chance to adapt subsequent chapters to the feedback.
I think as the ratio of completed works to in-progress works has increased (now, completed works probably dominate in totality, though Wattpad’s ranking algorithm keeps a lot of in-progress works in the hot-lists), members have become more interested in taking actions at the ‘whole book’ level. You mention another good reason to want to do this: re-posting after a whole-book edit.
But I still have the feeling that it’s a bit counter to the spirit of Wattpad to place and act on books all at once. Many writers - myself included - like to see the reader reaction as the chapters dribble out on a regular schedule. That’s why, though my own current book is finished, I’m okay with taking the time and effort to dribble it out.
What I would vote for it to make that process more efficient. Many people have asked for timed posting (you make all the chapters private, then have WP automatically switch them to visible on a schedule). I guess that would help in your case, too, if you could choose to make them visible on a 1 second schedule.
Wattpad’s web-based writer interface is also sadly clunky and function-poor. You can’t even center text (it pretends you can, but it doesn’t work, at least with the two browsers I’ve tried it on). Copy-paste is terrible - much worse than with other writer sites I know of.
A last point: I’ve seen a number of recommendation to NOT post an entire new work at once. Apparently that’s a good way to hurt your visibility and ranking and reader numbers. People will suddenly see a ‘Completed’ novel with lots of chapters and very few reads and votes. They will skip over it and not bother to try it, because the reads and votes are so much lower than usual for its length. Few reads and votes on a completed work - must be terrible, right?
I know you’re talking about re-posting, which is different, esp. if you are re-posting something you have not ‘un-published’. One Wattpad issue with respect to re-posting in any way, is that it removes all the inline comments. They get pushed to the bottom, where it is hard to see the context. To me, that feels a little bit disrespectful to the readers who bothered to leave those comments, so once a chapter has been up long enough to accumulate some inline comments, I try to avoid re-posting. I might re-post to fix some real awful blooper, but not to fix little things.
Anyway, thanks for starting a good thread.