Well most people in the UK have them as you need boiling water to make tea and therefore it makes sense to have an electric kettle rather than boil water in a pan every day. I guess if you don't drink tea then it's not an essential.

That being said a kettle is also useful if you need some boiling water for pasta or whatever: You heat it up in the kettle and then pour the boiling water into a pan and put it onto the stove. That way you don't have to wait for it to heat up from cold on the stove, which takes much longer.

It's just generally pretty useful to have something that can boil water quickly, and an electric kettle isn't exactly expensive, so it's kind of odd to me that more Americans don't have them.