I think Chopin felt the most comfortable writing for the piano, though it was not necessarily his favorite instrument. He was simply able to use it to its full potential and to express everything that he imagined in his mind. In many ways his writing for piano and orchestra is just and extension of that. It’s not symphonic writing. It’s not writing that uses the full potential of the orchestra. It’s his imagination for the piano enlarged by the writing with orchestra. It adds colors to the piano. We are given endless possibilities already at our instrument. But Chopin uses the capabilities of the winds and the strings, their richness, their sound quality to add to the piano’s possibilities and color palette. It’s a gift that he gave us with these orchestral pieces.
In a Mozart or Beethoven piano concerto if you removed the orchestra and told the pianist to play their part alone you’d be left with a bare bones structure. There would be some beautiful themes, some beautiful moments, and then there would be these very dull and uninspiring passages because you would be missing the core of the work. Now in Chopin if you take away the orchestra for the most part you would still end up with a fully-fledged and well-developed work. When the orchestra comes in it adds something- another layer- not instead of the piano, not in place of one of the piano themes or capabilities, but yet another relayer, and more beauty. (Jan Lisiecki)