1) Improvisation can enhance person's musicianship. By learning to create a musical composition, an organist will develop a better ability to recognize scales, intervals, and chords. In other words, skills in improvisation will also serve as ear training which in turn will improve general musical abilities of an organist.
2) An improviser will appreciate organ repertoire better. Because improvisation involves studying works of various composers, in turn it gives its practitioner enormous wealth of information about various historical music styles and national schools of organ composition. Indeed, an improviser will know ins and outs of every aspect of organ repertoire.
3) By improvising on the organ, you are continuing a tradition which is centuries-long. If you look back at the origins of organ composition, you will discover that the surviving organ repertoire is just a tip of the iceberg. The majority of music making on the organ was improvised. Many of important composers were also brilliant improvisers (Bach, Handel, Mozart, Beethoven, Mendelssohn, Chopin, Liszt, Franck, and Messiaen to name just a few).
4) Learn how the piece is put together. Because much of improvisation studies involve deconstruction of existing musical material, you will be able to analyze organ works at a very deep level. In fact, your analytical powers will become much greater whether you are looking at the music composed on paper or listening to a performance.
5) You can learn to recreate the styles of your favorite composers. Do you like the music of Sweelinck, Scheidemann, Buxtehude, Bach, Franck, Reger, Widor, Vierne, Messiaen or any other composer? It is possible to imitate the style and musical language of any composer that you love. Ever wish that your favorite master would have composed more works for you to play? If you learn to improvise, you will easily be able to play like your role models.
As you can see, improvisation on the organ gives many advantages for the organist. If you never tried improvising before, you might be surprised at how easy it is to start making your own music. Just get a good improvisation method book and start practicing developing your creative abilities today.
If you are interested in learning to improvise in the style of J.S.Bach, I highly recommend „Bach and the Art of Improvisation“ by Pamela Ruiter-Feenstra. The approach that P.Ruiter-Feenstra uses in her book is rather unique among other books on improvisation. It is not only a textbook with exercises but much more than that. The students who will be studying this book will acquire comprehensive knowledge about various 18th century performance practice aspects, such as articulation, fingering, and pedaling etc.
By the way, do you want to learn to play the King of Instruments - the pipe organ? If so, download my FREE video guide: "How to Master Any Organ Composition" in which I will show you my EXACT steps, techniques, and methods that I use to practice, learn and master any piece of organ music.