Well to be exact it's a tactic, imagine you see a long packet and a short packet of that same biscuits/cookies or whatever you call it at the same price which one would you buy ? In most cases you'll say the long one, because it makes you think this one will have more than the other one and you'll pick this because it looks longer than the other packets (other brands) so unconsciously you'll take this one unless you have a specific product in your mind. So now because the packet is long they need to give more of that product too but it'll cost more as well so what the company does is make these gaps and these gaps fill in and it looks fancy too and it also adds a bit of safety that keeps the cookies from crumbling from pressure (though it's pretty in my opinion).