Why must "happy and cheerful" be a prerequisite?

Isn't this a tad discriminatory?

In job ads in Sweden, it's not uncommon to see among the qualities they are looking for: "Happy, cheerful, perky".

Darn, and I met all the other qualifications! I have a university degree and 5 years work experience. Too bad I'm not happy, cheerful and perky! Oh well. Next time.

What business is my emotional state to a potential employer as long as I am qualified and know how to do the job? As long as I'm competent and know how to plaster a big old smile on my face even though I don't really mean it, that should be all that's required. Why do we have to be perky and cheerful anyway? Isn't it enough to be polite and genuine? Why do we have to be affected in order to achieve?

I am not, nor will I ever be, perky and cheerful. I never have been perky and cheerful. This is why I'm most suited for a job where I don't have to see any people. Stick me in front of a computer screen with a long translation, or better yet, a book to write. I may struggle and hate it while I'm doing it but I'm secretly loving it and enjoying every minute of not having to pretend to be perky and cheerful. Screw perky and cheerful. These are adjectives that are stereotypically associated with women, as if we all should naturally be sunshine and lollipops. Well we're not. We're just as filled with issues and conflict as men are.

Happy is something to strive for however. Happy is a goal to aim for.