Funnily enough, I started playing classical piano music at that time and only recently stopped. I felt the need to play the piano as it should be played. That's still an important cause for me. To develop musically, you have to really know how to compose. Writing a long piece is different from writing a short piece, and you can practice.
Composition is like improvisation, but very slow.
It's a million times slower. You can spend two days writing four bars. Improvisation is spontaneous, but when composing you can examine it with a microscope. Composition is an improvisation that you can spend a long time on, and one influences the other. But above all, composition influences improvisation.