AAR consolidation is (for those that can do it) a regular feature of modern ops.
Well yes, vasco. - it was also used a lot during GW1. But the squadron allowed its receiver skills to wither rapidly thereafter, so that the effort required by the AARIs to restore full day/night receiver capability for Bliar's bring-a-bottle wars was considerable. Particularly if that included receiving from a TriStar.
Not many nations have the ability to consolidate nowadays.
Given the proposed number of Voyager crews and the small number of KC3s, the effort involved in maintaining the necessary probe-and-drogue receiving skills would be quite considerable. The cost of retrofitting the Voyager to KC-30A standard would be high, as would be the training costs for boom operators and receiver pilots.
Desirable for Voyager to be able to receive or transfer fuel to another tanker? Yes. Essential? I don't think so.
A pity the RAF didn't go for the 'Airbus Industrie' MRTT proposals of 15+ years ago though. That included a cargo door, combi flexibility, either a probe or UARRSI, a boom or FRU and 5 rather than 4 ACTs - if I recall correctly, we were anticipating around 2 dozen of such aircraft, each with a 77.5T fuel capacity.....