Successful novelists weren't typically the ones complaining.

The novelists that were complaining were almost universally the less successful novelists who were upset that their 75,000 word magnum opus wasn't making them more money than a short story author who banged together a short story in an afternoon that managed to sell EXACTLY as many copies.

Under the new system, that novelist gets rewarded, at the expense of short story authors.

Did you hear novelists making 50,000-100,000$ per month complaining about short story authors eating their lunch? I sure as hell didn't, and I know quite a few of those people. They're singing Amazon's praises right now though, because they stand to make an absolutely obscene amount of money.

Amazon has come out clear as day and literally said they are changing KU to favor novelists. Look, here's what they said:

We’re always looking at ways to make our programs even better, and we’ve received lots of great feedback on how to improve the way we pay KDP authors for books in Kindle Unlimited. One particular piece of feedback we’ve heard consistently from authors is that paying the same for all books regardless of length may not provide a strong enough alignment between the interests of authors and readers. We agree. With this in mind, we’re pleased to announce that beginning on July 1, the KDP Select Global Fund will be paid out based on the number of pages KU and KOLL customers read.

I'm not talking out my ass here. Amazon themselves have said they are making changes to pay people based on length. The meaning of this paragraph is pretty damn clear. Novels are going up in value, shorts are going down.

And the way they've implemented it ensure shorts go down in value even if you have an overwhelming number of them.

Novels are worth more than shorts going forward. Period.