I agree with mjames to an extent; however, use your common sense and avoid injury. Right now I'm working on the Chopin etude in F minor, op. 10/9. In the LH, the first bit is an F-C (interval of a perfect fifth). This is marked to be played with 5-4. This puts unnecessary strain even on the largest hands. Perhaps it may not have been so in Chopin's day, as the keyboards were narrower, but on today's pianos it simply won't work that way.
As for your problem, Chopin's hands aren't your hands. I can't think of a single piece that I've used the exact fingering my score gave me in every place it gave me one (which with urtext editions is often sparse in and of itself).
You're right; fingering doesn't really contribute to the sound, it just makes the sound you want easier to achieve. Good fingering is a means to an end, not an end unto itself.