Well yea I think most if not all Sandy Bridge machines have UEFI already. Its just that not all of the machines have a fancy GUI that has been promoted a lot. In its core, it supports UEFI. However, manufacturer decided to put old BIOS looks instead of developing a brand new UI for UEFI. Hope this clears up your doubts.

It isn't useless..... Its just not in the form how its marketed. That is all. However, I do not have much experience with newer Sandy Bridge machines to justify whether current UEFI implementation speeds up the time taken to POST. A properly optimised UEFI can POST in just a second or two. I remember seeing a video of that years ago. Not sure how it is in reality today.