I don't think it's as simple as the article has made out. Many different airlines spec these planes for many different types of flight, and types of cargo - tha

I don't think it's as simple as the article has made out. Many different airlines spec these planes for many different types of flight, and types of cargo - that's why features are optional. E.g. if an airline operates many routes on which the hold is likely to contain a high proportion of hazardous material, they can spec the additional fire suppression system. Even with a single system, the plane's certification will require that it can contain a hold fire for {X} mins (long enough to allow the plane to land and evacuate).