Music Theory is an organize approach to what sounds good and bad, and WHY it might sound good or bad.
Do you NEED it, never...do you WANT it? At some point I hope you you do want to learn these concepts, and varistions, that have been passed down for centuries. If you think you want to be a musician and be able to COMMUNICATE ideas/concepts back and forth with other musicians...knowing the theory will go a long way. Even knowing SOME fundamentals will go a long way.