I think it's not just quality of US produced fighter jets that mage them top class air forces , it's also because excellent education they got from US Air force or Navy.
Example: Iranian Air Force during Iran-Iraq war
Regional tension (especially around South China sea) becoming hotter and hotter these days. Indonesia needs big stick and good relations with Super powers. We also need to balance our trading with US.
Eagles will smooth things up
Yeah but that was USAF price where F15 infrastructure and mechanics already well established. Not like here where Eagle is the whole new species for our Air Force.
Also because of some laws here, we have to get some offset.