Photo credit: Florida Georgia Line
If you don't think social media is important to an artist's career, look at what it's done for Brian Kelley and Tyler Hubbard and the rest of the guys in Florida Georgia Line.
These guys started out virtually unknown and worked hard as independent artists to get their name and music on the map making use of Twitter and every other social media outlet you can think of, internet and satellite radio (Sirius XM's "Nashville 57" and NixaCountry Radio), and taking the time to personally connect with their fans. By the time a label finally noticed and signed them a few months ago, they had already become a household name with their debut single "Cruise" being played from every speaker, every car stereo, and every MP3 player. They've gotten their first gold record and were presenters on the American Music Awards last night.
THIS is how marketing and promotion is done, pay attention new artists and even those established who are struggling. This is what can happen if you believe in your product, take the time to market it yourself and not leave it up to everyone else to do, trust your fan base and get yourself out there.