It can be nice when the kernel starts, to show the Fedora logo and not the tux one.
because any choice of artwork will be subjective, the easiest answer is to just go with the upstream default instead of endless debate over 'which logo is best'. it's also one more patch that has to be maintained forever, and we try to be as close to mainline as possible. (We already deviate way more than I'd like, and I'm trying to reduce patches instead of add more).