Misunderstandings create a conflict that can usually be pretty easily resolved. In order to have a good story there has be a good conflict, and it is even better if the reader (or viewer) doesn't see an easy way for the conflict to resolve itself. But in the end, we want the happy ending that romantic comedies are known for, so we keep reading or wathcing to see, not IF the story will resolve itself, but HOW the story will resolve itself. That is a huge element in the enjoyment of these types of novels and movies. When all is said and done, it doesn't take much to make a misunderstanding into a sense of understanding, so we are kind of along for the ride -- enjoying the moments of dramatic irony, situational irony, near misses, further complications, moments of near hopelessness, and finally, an interesting and satisfying to the end of the problematic misunderstanding that can bring about the happy ending we KNEW was coming eventually.