from the wikipedia page: The extensive curves and ridges of a Pepper X chili create more surface area for the plant placenta and locules to grow and retain c

from the wikipedia page: The extensive curves and ridges of a Pepper X chili create more surface area for the plant placenta and locules to grow and retain capsaicin, adding to the intensity of heat experienced when a Pepper X is eaten.[2]. So it could be an intentionally bred feature