The owlbear was inspired by a cheaply mass produced bag of plastic monsters from China.
Gary Gygax and the rest of his pals in Lake Geneva, Wisconsin (the very game that gave us the campaign setting Mystara, with Gary Gygax’s character, the wizard Mordekainen) kept their creative muscles strong by making up stories about the random cheap monster figures in the bag. Another one of them became the Rust Monster, for example. Some of these monster figures remain unidentified, perhaps, in a job for future game masters.
Owlbears need to become scary again. They were once described as “congenitally insane” creations of magic that were perpetually paranoid and hostile, creatures who shouldn’t exist who automatically grabbed you after 2 claw attacks, squeezed and could peck you, and with the grab, they’d do that damage every round. Every edition made them less and less scary, until the recent one, where they’re just treated as a normal animal with normal animal motivations instead of a thing created by experimentation that “shouldn’t be.” The grapple damage that made it so scary is no longer there.
Source: Vintage Geek Culture