Pretty sure it's not a necessity, as your main address is in the UK. I do think it makes things easier when it comes to administrative stuff. Not to mention if you have plans to eventually move back to the US. I'm really not sure how you would go about changing your US address though... I hope you figure it out!
I still hold an address in Ohio, which is my parents' address. Before I moved to England, it's the only place I ever lived besides when I was away at college. My parents are very "rooted," and will most likely never move until they can no longer keep up their home and property.
My driver's license, US bank account, and a couple bills are tied to my Ohio address. The Ohio BMV said I could still maintain my Ohio DL while living in the UK.