Double D's Facts Book - Formulaic does not equal bad.

The key is in knowing what you're working with and what you're trying to do. Don't try to do anything new or special or different if you can't back it up – you'll just make a big mess.

Star Wars started out as blatantly and deliberately formulaic and instead focused all its efforts on making the best it can out of that formula, and it turned out pretty great.

I like to compare "A New Hope" (I/IV) and "The Force Awakens" (VII) for a good and bad example of being formulaic.

"A New Hope" is just the hero's journey, but in space! It was a good start for a movie turned franchise, and even if some of the inherent ideas (young farmboy turned hero, old mentor, save the princess etc…) aren't that original, it still played them well, and in new and interesting ways.

Compare that with "The Force Awakens", which was accused of being a rehash. Than again it's one thing to have a hero go on a treasure hunt adventure in a jungle or the ocean, that's different versions of a formula. If there's another Death Star "but bigger and badder", than that's just copy-pasting past plot points.