That is correct in regard to general purpose prepayment cards.
However in regard to foreign currency travel money cards this is not really the case. These cards are the new alternative to travellers cheques, foreign currency or being ripped of by your regular bank and, as such, are popular amonst all. If you look at cards like FairFX or CaxtonFX they are designed with a regular card savvy business traveller in mind. They offer excellent exchange rates and infact some of them can only be loaded with debit card/bank transfer.
So in all likelihood the Nationwide card should be an alternative worthy of serious consideration by the majority of prepaid foreign currency card customers.