I'm a supporter of capitalism, and I will freely admit this. The caveats I will insert are two:
1) A strong state is required to carry out these wars, colonization, and rape of resources/peoples. Capitalism, being an economic system, says nothing about what kind of state structures we should have, other than that they should be minimally involved in market regulation/business transactions. If we hold also to the small government model, with a non-expansionist, solely defensive military, that I support, we would not see this.
2) Being part of the economic periphery, in which a country serves largely as a labor base and as the seat of key resources to be used by other countries, is simply part of the cycle that just about every country goes through before becoming first-world. Even the western world, which is so prosperous today, mostly started out on this periphery (outside of England, Holland, and France) once capitalism became the prevailing economic model in the western world. Today we can see India and China starting to shift in toward the economic core, and they will each be first-world nations, probably within a few decades.
In addition to these two points, I just want to reiterate that war and exploitation are hardly hallmarks of capitalism. First, businesses do not go to war with each other. Second, nations/empires/kingdoms/what have you warred with each other and economically exploited each other well before the world ever saw any economic model even approaching modern-day capitalism. Removing capitalism isn't going to solve any problems in that arena. Removing overblown state structures that have the power to do these things, however, will.