If I was thinking of emigrating anywhere and I knew the door would close in two years then I would bring forward my plans, if I found out it was closing in a couple of weeks I'd think it was already too late. I don't see why this is controversial.
Conversely, there may well be plenty of Brits who may well be concerned that reciprocal restrictions might prevent them from emigrating to the EU and might move forward their plans to do so too.