I'm new to bunq. I still haven't even received my cards. But the first person I showed the card design to in the app was a Brazilian friend, and his first reaction was asking if this was a Pride special design or something like that.
I am trying bunq as a candidate for my main bank because of its features and API, not because of its colourful design. Even thou I like the cards a lot, I understand that some people might feel uncomfortable or unsafe using them in some places. Sad but true.
So giving users a choice wouldn't hurt. Instead of going black or metal like every other bank, bunq could simply offer the choice of solid colour cards in any of the 12 colours used on its logo. You already offer so many customisations on card description, icons on the app etc... shouldn't be so difficult, right?