Everyone wants to rank for those broad two or three word key phrases because they tend to have high search volumes. The problem with these broad key phrases is they are highly competitive. So competitive that you may not stand a chance of ranking for them unless you devote months of your time to it. Instead of spending your time going after something that may not even be attainable, go after the low-hanging fruit of long-tail key phrases.
Remember when you used to rely solely on search engines for traffic? Remember when you worked on SEO and lived and died by your placement in Google? Were you #1? Assured success. Well, okay, maybe not assured. Success only came if the keywords were relevant to your site users, but it was the only real roadmap to generating site traffic and revenue.