Do I have to get nipples removed for breast reduction?

I would venture that is is almost never required to remove the nipple.  15 cm is not that long.  You have run up against a very old fashioned surgeon, or one that was poorly trained.  Find a new surgeon.

I almost never perform a free nipple graft, and my inclination to perform a free nipple graft will go up when the distance from the fold to the nipple is greater than 20 cms.  I have treated many large breasted women using a standard inferior pedicle.

Thank you for your question.  In my practice, I've never had to detach the nipple as part of a breast reduction.  This includes many breast reductions performed with sizes much larger than yours.  It's usually left as a last resort option if tissue viability is potentially compromised at the end of a case.  Be sure to consult with several experienced board certified plastic surgeons.  Good luck.