Primary Purpose:
Has there EVER been ANYTHING that could ONLY be manufactured in space that would be so valuable it would justify the development costs of designing and operating a craft (and all its associated support systems) dedicated to deliver it back to earth?

Secondary Purpose:
Critical, high-value payloads, such as vaccines, critical spare parts, or organs for human transplant can now be delivered anywhere on earth in a matter of hours using conventional aircraft and commercial delivery systems. The amount of time required to plan and execute any cargo mission involving suborbital trajectories (with the possible exception of a nuclear warhead) is bound to be much longer.

Tertiary purpose: Yeah. Maybe someday.

The only 'thing' of value which might need to be delivered super-quickly from one point on the earth to another is information, and that can go over the telephone.