Why shouldn't Britain get a Codification Constitution?

-Undermine Political Structures that have worked well - Parliamentary Sovereignty be Undermined -UK lose Flexibility in Constitutional Agreements. USA States have Restrictions on Handguns Carrying struck down from 2nd Amendment. UK can get Restrictions of Guns after the 1996 Dunblane Massacre -Uncodified Constitution allows Government to Govern. 2019 GE gave UK a Clear Mandate to 'Get Brexit Done' which gets Political Certainty up -Having that of USA makes the Supreme Court into Politics and threatens its Independence and Neutrality -Uncertainty over who'd write it, what goes in it. Likely that its written in 1 Place so Executive Power is Codified only, increasing Governmental Power which well what's the point