Just kill? Everything just kills! That is the way of the entire universe. The Daleks represent the ultimate evolution of life itself, the perfect species. When all other life is suppressed, completely exterminated!
[He breathes in and calms, his voice at the level of a fanatical whisper.]
Then there will be absolute peace. A single race, my Daleks, ensuring the continued death of all sentient life that could evolve. Protectors of the universe! Ending war, forever. The only possible form of universal peace.