Conrad's work positions the modern audience in 2015 to understand the full implications of Colonialism. The audience in 2015 probably possesses a greater degree of awareness about the European foray into indigenous lands than the one for which Conrad wrote. I think that Heart of Darkness positions an audience to become fully cognizant of how people were treated during colonialism. The idea of "savagery" existing in the perceptions of Europeans towards Africans, and in how Europeans treated Africans, is more accepted in 2015 than it was at the time of Conrad's original writing. The book positions the modern audience into accepting something that it most likely already knew.
I think that one unique element in 2015 that probably was not as easy to envision in the past is the dehumanizing effect Colonialism had on the perpetrators. After reading Kurtz's final words, "the horror" might be an apt description of how Belgians interacted with the Congo. It might also be an appropriate description of how Colonialism influenced those responsible for it. Colonialism is shown to be an experience that dehumanizes both the indigenous person and the European perpetrator. Given the modern audience's perspective on the topic of Colonialism, the book is able to position a reader to recognize that Colonialism and the abuses intrinsic to it dehumanized both intended target and perpetrator. In this light, Heart of Darkness acquires a deeper meaning for an audience in 2015 than in Conrad's time, which was largely ignorant of the full implications of Colonialism.