The ability to fiddle with page corners, half-flip pages then flip them back, that kind of thing, made it much more like reading a real book, and it was my favorite way to read ebooks, followed at a distance by e-ink readers, and then, very distantly, by every other non-e-ink way to read ebooks that wasn't Apple Books.
Not joking that the page flip animation was the thing that made the Apple version far and away my favorite way to read ebooks. The new animation doesn't just lose that quality, it's also notably bad even among the all-some-degree-of-bad animations of reader apps in general (not counting pre-16 Apple Books).
I gave up on e-ink readers a few years ago and donated a couple of them. I am reading books in eletronic format on iPhones. It's just more practical, I don't need to carry a second and usually larger device with me, and ... I don't need an external light when it's too dark to read. Plus, the newer iPhones with OLED displays are pretty good for reading.
I do use ereaders and if I travel for some time I'll use it..
I understand that it's useful to sometimes have access to books on a computer, phone or table, but that's for professional use in my mind, and not a replacement for a physical book in the same sense a device with e-ink displays are.
Even if you read on the iPad, I don't fully understand why you'd want the page animations anyway. Still the complain in the article is weird, just accept it and move on, if you're waiting for Apple to switch back I feel your going to wait a very long time.