This can't be helped as the US only recently lifted its sanctions on military sales to Indonesia. One can notice that most of the aircraft on the list is of US origin.
Secondly, there is also the budgetary problem as Indonesia is only slowly moving out of political instability and economic problems with the current president at power. If i am not wrong the military budget is been increased recently, i think partially due to the fact that an ex-army general is the current president.
Indonesia is a very large country with numerous types of terrain. The number of operational aircraft is clearly inadequate to patrol such a vast expanse of land. But such a situation will improve over time.