Why are the Modes Important?
To the best of our knowledge from history, the modes originated in Greece and were named there. They have been influencing music since at least the 9th century and have become increasingly popular since after the classical and romantic periods. Here’s an interesting little article on that, but what I would like to focus on here is why they are important for music students and musicians to learn to understand and play.
As you will note in the article linked above, some extremely well-known and loved music has been written in various modes. Who doesn’t know and love Scarborough Fair or Billie Jean? Because most modal music does not follow the same pattern as the foundational tonal centers of major, natural minor, harmonic minor, or melodic minor, it has noticeably distinct sounds and feels which make it fun, interesting, sometimes even exotic sounding.[1] This unique nature, sound, and feel alone is enough of a reason to make the modes worthy of study, because without a proper understanding of them musicians that have learned only their foundational 48 will often accidentally play natural minor instead of Dorian, or major when they should be playing Lydian, etc. [2]
Maria in major would not have the cultural nor the uplifting flavor Leonard Bernstein created with his beautiful composition, and The Jetsons would lose their characteristic spacey sound. Both of these compositions are in Lydian which has a #4, and not the perfect 4th of the major scale. The modes are also incredibly important for improvising, and not just in jazz music either, in fact Sweet Home Alabama, Norwegian Wood, and Oye Como Va are all popular modal songs often opened up for musicians to improvise at length over.
For piano and guitar players, the modes are also quite useful in that learning them requires them to learn new fingering patterns that will help with more complex melodic lines as they learn more challenging repertoire. For a musical breakdown of the 7 modes of major, see here.
[1] Ionian mode and Aeolian mode are excluded in this of course, because they are so common in Western music that we generally hear them and refer to them simply as major and minor (natural).
[2] By foundational 48 we mean major, natural minor, harmonic minor, and melodic minor.