Music. It's great to be able to write it to appreciate it. But it's not entirely necessary in order to do so. Music Theory is great, and your sweeping solos, insane drum fills, and your high octave wailing i'm sure will impress, but remember: It's not about you, it's about the song. If you can keep that in mind, you will succeed.
But about me...I play Drums, Acoustic guitar, and very occasionally Bass. I prefer that will benefit me, but i can stop to enjoy the little things.