Allergies. Very popular fabric softeners contain one perfume that makes me asthmatic, every year someone in the office has watched a fabric softener commercial and thinks they are a good idea.
Ingredients used for fragrance are known endocrine disrupters, eg. pthalates in personal care products, perfumes, and yes, laundry detergents and softeners. I really thought this was common knowledge, but not outside the chemistry community, I guess?