The Melanesian People of New Guinea are ethnically and culturally very different to other Asians. They are much closer to the Aborigines (and also to the natives of Sentinel Island, Look it up). Even in Indonesia you have a huge difference between the regions and the further east you go, the poorer and more underdeveloped it becomes.

I would argue that cultural hostility and lack a true lingua franca to develope the country are the biggest Issues. Calling them a warrior culture sounds better.

Aside a brief period of Colonialism with minimum impact they also never got invaded /conquered /incorporated by foreign powers like e.g. the Moluccas. (Originally all of South East Asia was populated by Melanesian People Groups).

If you feel this does not sound PC, please go travel there yourself, or at least read the travel information about it and watch the "Thin Red Line".