Samsung is so smart, they have very smart business strategisers. Giving source codes out will attract developers and subsequently attract customers. Whereas companies like motorola is locking bootloaders and keeping codes under tight.
Samsung knows that people want everything possible (in this case, in their phones) even if they do not need them (features)... it is human psychology.
This is really good for developers especially XDA and obviously for users, I wish I had enough money to buy this phone!!
This is one of the billion things that makes Samsung so awesome. Releasing their source codes and doing so quickly too. Very awesome.