I walk past/through Smithfields regularly. It's... nice? Ok it's not nice, it' uniquely London but it's just a pretty run down area in the middle of much nicer areas. But the plan was never to keep it, the plan was to knock it down and tell the people who had been working there to go work in Dagenham. So in my view this is no difference. That area of London just doesn't make a whole lot of sense for a meat market anymore, and while you can preserve the buildings you can't preserve a set of businesses that look sillier and sillier by the day. At some point you have to ask what you're actually preserving, because "Smithfields Market (rebuilt in Dagenham in 2025)" isn't really that historical.