Keywords are the only thing which people used to place in search engine boxes when they want to know about that particular topic. On the basis of that keyword, search engines like Google shows their search results so that users can get information.
If you will not target any beneficial keyword then you wouldn't be able to rank in search engines. You cannot drive organic traffic to your website. You cannot drive sales from search engines to your website.
Every keyword has their own importance, has their own monthly searches. Targeting keyword with having high monthly searches can drive you high traffic from saerch engines.
In short, keywords are most important to drive traffic to your website. I hope you understand what I explained here.