I love surnames about as much as I love first/middle names, so including them are important to me. But I know a handful of people who play my games completely exclude surnames all together. So, I've gathered that they're not as interesting to everyone.
When they aren't included in a game, I generally use it as an opportunity to pick my own, which is sometimes more fun.
"Mustn't be afraid to dream a little bigger, Darling." - Inception