It's a retail sales thing. When people shop, they typically use a really poor price comparison algorithm. If they see something bundled together, they will assume that they are getting it at a discount, and they won't actually bother to price compare.
The retail sales mantra is to increase the average price that a customer spends per purchase. If you can sell them a higher price point item under the illusion that they are saving money, then you've won.
I'm certain if pressed on this, they would claim that the gift pack simplifies the purchase for a new player. Ie: This set contains all that you need to start play. We've bundled it together for your shopping convenience. Now, you wont' have to waste your time/money trying to figure out which books they will need. Or some such nonsense.