The vision of the EU was always as a political union, rather than an economic one, even if this was not emphasised when we joined. Regardless, the point is that know we'd know what we are getting into. The electorate may, or may not, wish to join it with that full understanding (although with perhaps less of the propaganda that still permeates your post: we have always had control over our borders, whether in the EU or not, and if you've had problems with how we've controlled them in the past then you should look closer to home).
But in the end, my point is that this isn't a decision for the next election. Or the one after that. Or any GE at all, really. No doubt there will have to be a "first" party to make the move, but if Labour and the Tories remain split on this then the question is no more resolved by the "Rejoin" side winning. They'd *both* need to agree to it. And, by this metric, it's not going to happen any time soon.