"Brexit was not an “outburst” or a cry of despair or a message to the European Commission. It was an eviction notice. It was an explicit withdrawal of the legal sanction under which Brussels had governed Europe’s most important country. If it is really Britain’s wish to see its old constitutional arrangements restored, then this notice is open to emendation and reconsideration. But as things stand now, the Leave vote made E.U. rule over the U.K. illegitimate. Not illegitimate only when Brussels has been given one last chance to talk Britain out of it, but illegitimate now. What Britons voted for in 2016 was to leave the European Union—not to ask permission to leave the European Union. It is hard to see how Britain’s remaining in the E.U. would benefit either side."
Repudiating the deal that was made with the EU makes it impossible to negotiate a better one. The first rule of negotiating anything is that you have to establish trust that you are willing and able to fulfill what you agree to. It's not a rule that is imposed by the other party, but by logic, which means there is nothing that the EU can concede that would help.
