I think there's some issues there also with building new facilities. When ANI moved to the larger hangar they spent a fortune refurbishing the hangar and moving the DGCA calibration office to a smaller hangar. Given all this expense and the large area of vacant land there why weren't they allowed just to build another hangar ? The biggest problem with Curug is getting there by road , I have done trips where it's taken 3 hrs one way.
Which really is a shame because like you say expansion at Halim with TNI AU is pretty much a no-go. Also a ramp-up of operations there from an urban 'planning' (yes I said it in reference to Jakarta!) point of view wouldn't be ideal. Just seems that Curug would be ideal for an aviation business hub.
I think it took about an hour and half to get to Ciputat in afternoon traffic. But I can certainly see it taking 3 hours. That is the problem with Jakarta though and its good to see SBY again floating the idea of moving the administrative capital away from the Big Durian.
Don't suppose you know what is happening with Kuala Namu? I've still yet to positively sight it from the air although I have seen some pictures on the net.