There are plenty of "Real-World Threats" that the JSF would be able to address, don't confuse the EFT with the JSF, even with tranche 3 the ground package for the EFT is just a bolt on, the JSF has been designed from the ground up as a strike fighter.
Force projection is very important in any potential war zone, this is doubly important for an island nation. A US Carrier Strike Group (CSG) is as much a deterrant as it is a solution. When you look out of your window and see a carrer, a cruiser or two, 3+ destroyers, 2-3 guided missile destroyers and a submarine or two (you don't see these), you start to rethink your actions.
We don't have a shortage of defence spending in this country, it's just that so much of it is spent on projects that never materialise or are largely pointless anyway. The whole concept of building the equipment ourselves when not one of our industries can compete with the likes of FN and Boeing. The last time we tried was with the A400M and look at the mess that's turning into.
Back to the original point, there are plenty of situations in which a ground attack aircraft could be useful even in places like Afghanistan.