Seriously, bunq is a small, SEPA-centric bank.
USD accounts are a niche functionality that only a handful of their customers are going to be interested in (and TransferWise has already occupied that niche). Also, what would be the point of having a USD account with NL IBAN? You wouldn’t be able to make or receive U.S. domestic transfers anyway (except via TransferWise) but instead incur SWIFT fees.
I would like to to have multicurrency accounts - but I highly doubt it’s worth the development resources and future complications (you have to support it).