@bluedolphin-- You're not the only one who thinks that. In 2014, several Seattle columnists said that Seattle needs a new nickname. And many pieces have been written on the topic since. I've read quite a few satirical articles with funny recommendations for nicknames.
I don't know if Seattle needs a new nickname or not but if it's going to get a new one, it should probably be something that sort of comes about on its own. Perhaps the reason why some people have never really liked "Emerald City" is because they never had a say in nicknaming Seattle. A nickname doesn't need to be fancy or even serious. It can be unique and funny, as long as it reflects what the city is known for and successfully attracts visitors.