Actually the border here never closed, except the land border with Canada. You just can’t enter directly from the UK unless you are a US citizen, green card holder or spouse of a USC or GC holder or parents of a minor USC or GC holder.
Well yes, that's true, but as US citizens who live in the UK we aren't allowed to leave the UK for 'leisure' purposes, which includes visiting family members unless they are ill/dying/deceased! So 'open' border or not, our citizenship means nothing and we still can't go.