IMO, it would show the power and value of the EU. The UK would be far more willing to admit that they shouldn’t have left if they can get back in. The EU stands to gain from such a prominent country (and one that can say so from experience) undeniably admitting that it’s better to be in the EU than to leave. That’s some stellar advertising of the economic value of the EU.

Though they definitely shouldn’t bend every rule to let them back in. The pound should be replaced by the euro. It’s dumb that the UK got that exception.