It's time for NS to come out of the stone age and stop being hostile to foreigners. Someone should write to Timo Huges (their CEO) and explain that NS is not fulfilling its social mission by adding so much red tape to non-dutch residents.
It's all about volume... The current payment structure works for 99.9% of transactions so there is no real incentive to implement more costly payment methods like accepting credit cards.
And the NS-machines at Amsterdam Schiphol and Centraal have been the exception accepting credit cards for a while, simply use those and pay the € 0,50 extra fee.
And in March 2014 they have expanded the option to:
Amsterdam Duivendrecht,
Amsterdam Bijlmer Arena,
Amsterdam Sloterdijk,
Amsterdam Zuid,
Rotterdam Centraal,
Den Haag Centraal,
Utrecht Centraal,
Eindhoven,
Arnhem,
Maastricht,
Groningen,
Hengelo and
Roosendaal.
So not so much to complain about these days.