I discovered that this rubbery coating is also applied to books! You know, some books have this rubbery, satiny feel and are very matte in appearance. Today I got my Adobe Photoshop Elements 2018 Classroom in a Book book and it had the rubbery feel and matte finish. The bookseller had put his own sticker on it. When I removed that sticker it left a sticky glue layer, so I took denatured alcohol and wiped the sticky glue layer off. Surprise, surprise, the area that I wiped became shiny. I then wiped the hole front and back cover with denatured alcohol and now I have a nicely shiny, good looking book.
So, they add another step in the manufacturing process, using what I expect are environmentally unfriendly materials, increasing the cost of the product and giving the book and unnatural look and feel. What a waste of resources and totally unnecessary, except maybe in the eyes of some sick marketing dudes/dudettes. I'll protest this rubber-skin approach every time I encounter this in a bookstore or online. I have some other books with this ridiculous "feature" and wonder what they will look and feel like in a couple of years.
I can understand the idea behind applying this kind of skin on cameras and other equipment to improve the grip, although it looks like it's backfiring after a couple of years. On a book, it's totally non-functional and unnecessary.