Many, many reasons.
Just a few:
1) To prevent the product from being damaged
2) To keep the product fresh
3) Advertising of the product
4) To inform the customer what is contained in the package and all other necessary information
5) Bigger packaging makes a tiny product more visible, therefore better possibility of a purchase
6) Slick packaging is a quick attention grabber (advertising)
That's just a few.
Just a few:
1) To prevent the product from being damaged
2) To keep the product fresh
3) Advertising of the product
4) To inform the customer what is contained in the package and all other necessary information
5) Bigger packaging makes a tiny product more visible, therefore better possibility of a purchase
6) Slick packaging is a quick attention grabber (advertising)
That's just a few.