IMO theory, in some form, is essential to any musician. If you know how music works from a general standpoint(i.e your scales, chord formations, tri-tones, etc...) then you can then apply those generalities to more specific topics. Also, if you don't know any theory at all then how can one read music(yes, you can play by ear, but still if someone puts a sheet in front of you and says play this then what are you to do. And yes it does happen, its happened to me on many occasions, thats when i silently thanked God and Classical Music training xD)
But anyway, No one can expect to play any type of music with out learning theory. It is inevitable that as a musician you will be exposed to theory at some point in time. So might as well learn it now. You never know when you will need to play something that you have never heard before from a sheet on the spot. So having a strong backing in theory will help you.