Rewards Club Coupon Printouts - Necessary?

I've noticed the more that I give out my information to various places that I shop (willingly, mind you) that more of these clubs distribute things like coupons and such in physical form. I'm curious why they feel the need to either print out these coupons, or why they require me to print them out. I'm sure that some of it is because of antiquated Point-Of-Sale machines that only understand a physical coupon, but I'm sure that if they support some form of "rewards club" membership, they could support a sort of discount with that card.

Say for instance that Borders has a 33% off coupon this week. I'm required before I make my way to Borders to print out a coupon and present it upon my purchase. Why? Why not have it so I don't have to print out the coupon? I already get an e-mail from Borders with the coupon. Why not make it so that I can just show up at Borders and get the 33% regardless of whether I have a physical paper coupon or not?

There may be some psychology that I'm not taking into account (the physical nature of a coupon being a larger driver to visit the store than the reminder in the back of my brain) but I'd like to know the reason why companies (and Borders isn't the only company to do this) have to have a physical coupon.