Why would I ever not use instant wire transfer?

Why would I ever not use instant wire transfer? About a year ago, it has become mandatory for banks in the SEPA to offer instant transfers for wire transfers between SEPA bank accounts, free of charge. Since then, every time I do a wire transfer, my bank's online banking system asks me whether I want to do it as a free instant transfer or not. Would there ever be a situation where not choosing instant transfer would have some advantage for me or the receiver? Or is it just the bank's slim hope that some people might click "no" occasionally so they can pocket a few days of interest? (If I intentionally wanted the transfer to happen later, then there is also a separate option for doing the transfer on a specific date, so that would not be a reason)