I think that while registries can seem like you're fishing for gifts...it also is very very helpful to the guests. No one wants to get a duplicate or a pattern/color the couple hates.
Plus nowadays, people have often lived on their own for a while and might have certain things...it's no longer the bride getting married at 18 straight out of her parents house and having NOTHING so that pretty much anything you got was fine.
For example, if the time ever comes for me
I have my mom's china and my grandma's silver. I would hate for people to purchase those things when I don't need them.