It drives traffic to Etsy, it gets items sold which might otherwise be ignored, and if you ignore most of the comments from the other users, it's pretty good fun. Sure, there are some people who are just mean or rude, but mostly the sellers themselves enjoy it (and if they don't, the item can be removed). Most of all, the site raises money for charity - t-shirts and other items featuring favourite picks are sold on Zazzle, and all proceeds are given to chosen causes, or the money is used to ask crafters to make items needed by the causes. Most recently, the money was used to buy knitted false breasts for women who've had mastectomies.
Have a look, ignore the snarks, and take it in the spirit it's meant, and you'll find something about it to enjoy.
http://www.regretsy.com