But on the other hand, knowing exactly what they want can be tough. Often customers (especially relatives and family friends) don't know what someone has already read (for my example), or has a hard time pinpointing what to buy someone. When it's easy, great. When it's hard, I feel a gift card says you know the person well enough to shop at that store.
Plus, in my case at least, receiving a gift card to someplace I shop frequently is great because it means I can buy stuff without expense to me. (Like when my parents got me a gift card to my comic shop for my birthday.)
Point being, sometimes it's just as great giving someone a gift card and reliving a bit of their spending, or letting them choose exactly what they've been wanting for a while but haven't told anyone.