People are free to replace their cards for any reason that they wish.
You’d expect someone to replace the card if the chip wasn’t working. Well, for some folks, including the original thread poster - the colour of the card is clearly also an important factor. It’s an important identifier, and to have a strong, solid shade associated with your product is something that most companies would like to have. You might even find that some companies actually change their design and colours after years in order to attempt to capture the same thing.
I don’t think there’s any significant environmental impact from a tiny proportion of users not being happy with the exact print shade and ordering a replacement on that basis. After all - it’s an anomaly, rather than the norm.