According to Dumbledore, why is the book, Fantastic Beasts and Where to Find Them, now available to Muggles?

Dumbledore, in the Foreward, explains why this book is now offered to Muggles for the first time. In Harry Potter's world, the book can be found in the households of nearly every family that practices wizardry, Dumbledore tells readers. He says that the book is in its fifty-second edition, attesting to its usefulness and importance as a scholarly textbook.