Club Penguin has removed the FUN and Animated Paint by Letters Books and I know that I’m not the only one that miss them! I asked Club Penguin why they are removed and I got this answer:

“We decided to remove the Paint by Letters books from The Book Room since they weren't being used very much. Did you know that these books were only ever available for penguins in English? Now that Club Penguin is available in five different languages, it's really important to us to make sure penguins gets to experience all of the same awesome features, regardless of the language they speak. Since the books weren't being used very much, it didn't make sense to translate them into all of the different languages, so we decided to remove them instead. I know this may be upsetting for some penguins, since the books were pretty cool and fun to read, but hopefully they'll be able to remember all of the awesome stories they created.”
Thanks for the answer Club Penguin here are my thoughts and ideas:

I think the problem was that most Penguins don’t even know that the Paint by Letters Books existed and that is a BIG reason not so many use them! To solve this problem you could add a Stamp for each Paint by Letters book under Activities that would be earned after we had found ALL hidden coins in one Book :) For young kids the Books take a while to Type so it would be good if you raised the total amount of coins to earn from 800 coins to 1200 coins :) When all three Paint by Letters Books Stamps are earned we should earn Double Coins every time we Play :) I LOVE the COOL and FUNNY Paint by Letters Books and I really hope you will rethink your decision and add them back :)

…If you too just like me want these Books Back you can write to Club Penguin and kindly ask them to add them back to the Book Room :)
Paint by Letters Books Game in Club Penguin :)
UPDATE: Thanks Anonymous for reminding me that Club Penguin never added the Paint by Letters Books among the Games on Map!