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. 
