Choosing a passport (no dual citizenship/passport dilemna)

[boysenberry]

I was wondering whether anybody knows what things one must consider when facing the dilemna of selecting a foreign passport to adopt if your parents come from a foreign country which does not offer dual citizenship/passport. I am Australian born however I am uncertain whether to get a foreign passport or an Australian passport, anybody faced similar problems? Which one should I choose? My parents come from Indonesia by the way and I am Australian born. How can I make an educated selection? What are the pros and cons exactly? I've heard that if I use an Australian passport to stay in Indonesia long-term they will give me hefty fees however if I go to Indonesia with an Indonesian passport they won't charge me at all for some reason. Indonesia is also considered one of countries on top of the terrorism watch list and I trust the Australian government more than the Indonesian government. I may be interested in living in other foreign countries in the future too, so does anyone know having which passport will cause me less trouble/hassle?

Also, does anyone know why many countries don't allow their people to have multiple or even dual citizenships?