Think about it, every country that is in conflict/in the face of danger put a heavy emphasis on dispersal. Sweden, Taiwan, Pakistan to name a few. Just look at how the JAS-39 Gripen are designed, or the annual Han Kuang exercise in Taiwan.
Whatever upgrade Indonesia invest on its air defense will likely collapse in the wave of overwhelming enemy attack, we could not wish (due to monetary and geographical constraints) to rival the dense air defense of Baghdad in 1991 to protect all our critical infra.
Talking about agile deployment, the E-2s are equipped with tailhook as standard. We on the other hand operate the BAK-12 mobile arresting wire. It would be a huge advantage for the E-2 to lets say fly from one base and to land in the many airstrips in the archipelago, thereby adding the complexity in which the enemy could attack those assets while in land.
No other AEW&C system could give these advantage, but I'm open for correction.
Off course in the long run, air force should seek a more capable and proper AEW&C, we should look at Japan with their high-lo mixed fleet of E-767 and E-2C/D. But for the moment I think more airframe are needed rather than ultra expensive high spec specimen which we could buy in limited numbers.