They may not have had a choice! When I had a high-profile job and had the use of a 'company' jet the rules were that no two people of high status in the company could travel together. This was a condition of use for the plane, the poor pilot had to make seven trips across Europe when he could have done it in two if we were allowed to die together so to speak. All down to the business insurance company.
I for one think that the Spice Girls reforming may be a good idea.
It may allow the ones who followed them around the first time, to see what I and most other people, knew at the time.
They are a manufactured, and talentless group of people, (in my opinion) who mime or "lip-synch" whilst doing "live" concerts, and who would have been just another group of people, if it hadn't been for the efforts of their publishing and presentation people.