But EC.Sylvania, remember, this is the Warhammer universe. Factions like "the Empire" will have to appear reasonably good fluff-wise, or things like the "Conclave of Light" would lose their credibility.
While I can imagine Tilean mercenaries looting their way through the countryside, looting wouldn't fit Empire fluff (except maybe for the Free Companies). Unless, of course, you want to apply imperialforge's historically correct attitude and amass über-huge armies trying to outstarve each other ála the 30 years war, and a fourth of the Imperial population in the process.