Remember the slogan ?United We Stand, Divided We Fall?? This is most likely the WTS? viewpoint with regard to why JWs should only use the accommodations on the approved list. A united group has greater bargaining leverage for not only prices but for getting the hotels/motels to ensure that a specific number of rooms will be available for those attending the convention or assembly. Of course an individual JW can stay wherever they please but this weakens the WTS? bargaining position, thus JWs are strongly urged to use only the accommodations on the list. It is all about doing things in a businesslike cost-efficient way.
FM