I have to say that one should learn as much theory as possible. You should also train your ear, to play by ear. The two go hand in hand. I learned a lot of things by listening, but I understood what I heard from the theory that I have learned. Theory opens a lot of secret doors, that people may not tell you about. I'll give you an example. The Lord has allowed me give a music workshop at my church. It is the first time for this body. I am teaching all of our musicians and our choirs some basic theory. Even though, I am not a drummer, nor do I play the clarinet; the theory for the most part is the same across the board (As far as notation, timing, etc). Now I would have never been able to do such a thing, if I just played by ear. The theory that I have learned, has allowed me to understand other areas of the art. I say learn as much theory as possible, because it is the foundation of the music. As long as you have good foundation, your creativity can be endless.
Now I must say, I heard some cats play and I wonder how much theory they have learned. Simply, because the run that this dude just played, wasn't in the books that taught me. I just credited to the fact that he has a creative mind, if he didn't learn from a book.
I leave you with this. To me, it is like building a house. As long as you know how to lay the foundation, you can build any house you want. A lot people want to build a nice stylish house, but never learn how to lay down the foundation.
God Bless.