Most distributions install a additional boot loader on an UEFI system. UEFI
itself is a boot loader, it offers a menu to select different operating
systems or individual kernels. Furthermore, the UEFI settings can easily be
altered with userspace tools like
Kernels since 3.3 support EFI_STUB, which means the kernel can be loaded directly from the UEFI. What's the reason distributions decide to use an additional boot loader? Most tutorials on Linux/UEFI focus mainly on how to set up the additional boot loader (rEFInd, grub2, ELILO, etc.) instead of booting Linux with EFI_STUB.
The only thing missing in the distributions is support. Since most distributions chain a second boot loader, the kernel is not added to the UEFI boot menu, nor is it copied to the EFI system partition.
Three scripts are sufficient to do all the magic. One which copies the initramfs to the ESP. A second one copies kernel to the ESP and creates a new entry in the UEFI boot menu. The third script removes the old kernel and initramfs from the ESP and deletes the UEFI boot menu entry. This allows fully automatised kernel/initramfs updates/purges without user interaction. I am using this approach since more than a year and it has worked flawlessly.
Why do most distributions use grub instead of EFI_STUB?
EDIT: I'm not talking about removing grub support entirely but to offer a
choice for those who want to use it for various reasons. Distributions could
provide a package
grub-efi for those who want to chain UEFI and grub and a
efistub-boot which contain the scripts I mentioned above.