Fabric is an extremely important component of your clothing line. First, it contributes to the cost of the clothing. Next, different fabrics require different manufacturing processes. Some fabrics are more durable than others and will be less likely to be damaged during packaging, shipping, and on display (and when being tried on by customers). Fabric affects shipping and packaging costs, both from your factories and warehouses to retail outlets and, with e-commerce, to the customer.
Fabrics also affect consumer buying decisions. Different fabrics appeal to different market segments, with some preferring "easy care" and some the prestige of fabrics such as silk, cashmere, and other fine fabrics which require dry cleaning. Different fabrics are fashionable each year, and thus the clothing manufacturer and retailer must be responsive to changing fashions in fabric content and texture.