If I didn't know any better I would take this question offensively but let me tell you, poetry isn't useless in the least. As a matter of fact, no subject is useless. To poetry enthusiasts and poets themselves, it is a means of expressing how they feel and beautifying it in the best of ways.  

It is quite possible that you're not good at a subject or do not enjoy studying it and so you think it is unimportant, but to someone else, those subjects may be an inspiration to do better and learn more. No subject is useless by nature.