In Which I Am Proud of My Bruises

Do you know why some really, really prominent children's books - like the last volume of a certain boy wizard series - are edited so badly? I'm certainly I'm not the only person who read through the last few installments of Harry Potter thinking OH MY GOD CUT CUT CUT!!!!
The obvious explanation is that a bigshot author can demand their immortal prose be left untampered with, on threat of decamping to a different publisher.

Yes, in large part.

Another still more depressing possibility is that the publishers just don't care and skip the editing process in order to get the big-name book out there bringing in all that lovely money as soon as possible.

Yes again.

But if the latter, that seems short-sighted, as a well-edited book is surely more likely to stand the test of time and keep making money for the publisher in future (if, of course, that publisher retains the rights - if not, maybe they don't care.).
It's certainly difficult to imagine that Bloomsbury couldn't find someone competent and willing to work on HP. Was there some poor editor weeping in her office over being prevented, by authorial ego or sales department supremacy, from doing her job properly?

Yes, that's possible. There are also a few editors who, unfortunately, just don't really give a crap.

I agree with you that there are further books in certain series that could have done with a sh**load of editing beyond the editing I know they received. (Never assume they weren't edited at all--they were.)

But I'd like to say a couple things about the short-sightedness of publishing, to provide some context, without actually defending it.

For one thing, for 99.99% of books, publishing is about the now. Being able to sell 500,000 copies now is the very best most books can ever hope for. Trying to create a book 'for the ages'--a book that will last past the author's own lifetime, nevermind just making it to two years from now-- is playing with such long odds it's ridiculous. That's a fact of the industry, and something to bear in mind.

It's also worth remembering that as long as the first book in a series is in good enough shape to keep hooking readers, it doesn't matter so much how badly plotted, excessively adverbialized, and padded with filler the last books are. Readers will still want them. That's a fact of the reading public.

So yes, sometimes authors prevent editors from doing their jobs. Sometimes publishers prevent editors from doing their jobs. Sometimes editors just don't do their jobs. And sometimes it's a combination of all three.

It takes a lot of fight to be a good editor. And it also takes knowing what fights are worth fighting.