In marketing if everything is to open - there is not enough certainty to the piece, there is to many things open to question it will lead to too much doubt and confusion.

On the other hand you can have campaigns that have to many closed ends - you become predictable and boring.

Now marketing is not a movie - the goal is not to entertain - but mystery with certain pillars of certainty to grab onto give the customer something to explore and imagine.

Make sure there is always a little bit of mystery and controversy present. How many open ends are there compared to closed ends? Is there room for the person to be certain but to also imagine?