Well, it has to be interoperable so that it has the ability to do what's known as RAS, refuel at sea, with NATO allies.
Bigger navies would splice up the capabilities that we're trying to put in the JSS into a bunch of different ships. The Brits would have a straightforward ship, like the Tidespring, that can refuel. Then they would have another class of ship, aircraft carriers, for example, that have almost an amphibious-like capability to carry a large number of troops and a large amount of cargo. Australia does, as well. Of course, in Canada, we stopped seeking the big honking ship, as former chief of the defence staff Hillier wanted, over a decade ago, and focused on this particular model.