Well, the more music theory you know, the better off you are. Having music theory knowledge helps you to hear things in your head that you wouldn't have thought of otherwise. For example, I've been working on this "boss battle" loop recently, and I didn't know what key I was writing it in. It was based off of these notes...
G# A# B C# D E F#
So I googled it after some in depth study on modes (I memorized them!). Did you know there was a mode called the "G# Locrian #2"? Yeah, I about died when I realized that was a scale, but wait, there's more! In fact, there are bunches of scales. I knew of major and minor scales, and then the idea of modes. But there's numerous scales to work off, and numerous chords to go along with that. The more you know, the bigger pool you have to draw ideas from. You start learning to know what sound you want. It's a beautiful thing ;)