Though it seems like Porgs were created as a great way to sell toys, similar to Ewoks in Return of the Jedi, Porgs had a very functional role in the latest installment of Star Wars.
According to the films’ creators, they were faced with a challenge when filming on the island where Luke took up residence. That challenge was being able to film the natural environment while respecting the natural wildlife.
The Puffin is a bird native to the island and were vast in numbers. To the point where it was impossible to shoot without them being seen on film. The filmmakers decided the best way to camouflage the Puffins were to create a new animal that would blend in with the natural environment and from this, Porgs were born.
Audiences, regardless of how they felt about the film itself, tend to agree that these fun and adorable creatures were a highlight of the film…and provide a great source of protein for Wookies.