I’m an American, so it’s maybe hard to put myself exactly in the same shoes, but if I were in the EU and able to act freely, I’d personally make the concession to permit the opt-outs to the UK if it permitted for Rejoin (that is, I don’t think that there is great harm, as things were working all right earlier and that any precedent concerns could be addressed arguing that this is a special case)

The EU would be nigh insane if it were to grant the UK its previous opt-outs, in my opinon. They only got them in the first place because they acted as though were special. They never really committed to the idea of the Union and kept using their potential exit from the union as a bartering chip. But, unfortunately them, they fell flat on their faces when they actually left.

And, honestly, things were not all right before; the UK loved to block just about anything that went beyond trade deals.

The EU has nothing to gain if it went back to giving the UK special treatment. And not really a reason to do it, either, because the UK needs the EU much more than the other way around, as the Brexit negotiations demonstrated clearly.

Giving them back their opt-outs would be like giving in to a child that keeps throwing tantrums when things don’t go its way. If the UK wants to come back, then the EU cannot allow anything but a regular membership – if it greenlights the UK’s application at all.