There is no right answer, only assumptions and theories, since we're talking about matters of culture, and matters of the heart.
There is right answer. There always is. Of course, to find it we need a crystal ball to look into the possible consecuences of every single decision and see what works better. Since we can't do that, we need to get closer to the right answer with as much information as we can.

Usually, when Westerners ask 'why', it leads to them saying 'it's our fault', which leads them to say 'those poor people, we did them so much wrong', which makes them keep their soft, impotent arses on their comfortable metaphorical chairs, and not act against the aggressor.
We did them wrong. It dosen't mean we don't have to do anything about it, but yes, a great deal of the damage was caused by western countries. Western countires are greatly responsible for the current world, since it is a consequence of the age of colonizations. You don't like it? I am sure the Germans aren't proud of nazism, the Turkish about the crimes of the Ottoman Empire, the western Euorpean countries of crusades, the Russians of stalinism...