I think that learning theory of music is quite important to learn alongside of learning to play the piano. While I think it is important, I am not saying everyone must learn theory beyond the basics. If you choose to learn theory, you will then enhance your ability to play more complex piano music. This is true for all genres of music.
If we look at the classical music genre, playing this type of music is extremely dependant on your ability to read the musical notation. If you don’t understand a symbol or a marking on the music, then how is it possible to be able to play it accurately if you don’t understand what it is, and how it affects the music? Infrequently used, or obscure time signatures, really high or really low notes, dynamics and ornamentation are really impossible to play unless you have the knowledge, which is only gained by learning theory of music.
If we were to examine popular music, we would find a genre that is heavily dependent on playing chords. Unless you have the knowledge of augmented, diminished, 7th chords, dominant 7th chords, 9th,11th and even 13th chords, you cannot play these chords, which would make your music far more interesting to listen to. Even if you were stuck with only being able to play major or minor chords, these are only learned by learning theory of music.
As far as the jazz music genre goes, it requires some classical music theory knowledge and the popular music genre’s knowledge of chords to be able to play jazz piano.
As you can see, all the music genres require some theory of music knowledge in order to be able to play to an intermediate or advanced level. Theory of music is necessary.
So many people decide that learning theory of music is boring and it certainly could be perceived this way simply because it is not as fun as playing the piano. Theory of music has a reputation of being hard or boring – but this is not necessarily the case. If it is something that appeals to you, it can be very interesting. Let me explain it a different way: I am no gardener. My garden consists of plants that are considered unkillable for the climate. If I try to read something about companion planting, or moisture levels for certain plants, or how to fertalize certain plants, I get bored. I am not interested in gardening and as a result, I find reading anything about gardening very boring. My point is that theory of music isn’t necessarily boring, it is boring only to those who are not really interested in making music.