People only seem to be looking at the instant £60 benefit to Rovers and not the longterm benefits.
Presumably the club will be able to collect lots of data on the fans, demographics and spending habits (so they can cater more specifically to each demographics needs. I.e. Finding out men aged 41 are more likely to buy a scarf then a 31 year old female (and therefore design a scarf taylored to the older male market = higher sales).
Additionally they will be able to sell the data of the fans spending habits on sites such as amazon or wherever they offer discount with the card to marketers.
I think this is a tremendous 21st century idea by the club with longterm benefits to the club (and hopefully the fans) and not just a get rich quick scheme.