1) Achieve Economies of Scale and Scope - The largest (post-merger) food company in the world could provide manufacturing, purchasing and logistical advantages.
2) Gain synergies with current food subsidiaries - The merger of two companies should allow a firm to pool production and attain lower operating costs. The economy may come from reduced overhead or the ability to spread a larger amount of production over lower (consolidated) fixed costs. There may also be differential management capabilities: an efficiently managed firm may acquire a less efficient firm with the intent of bringing better management to the business. Efficiencies can also be gained through pooled financial resources or simply through pooled risk.
3) Tax Shields from re-levering Kraft - Kraft is seen as being over equalized pre-offer. Perhaps current management is overly comfortable, with less concern for equity value.
4) Soften corporate image - Cigarette executives expect rough times ahead for their industry. If they look closely at the 'big picture' and change their image to a diversified food producing company, these threats may become partially mitigated.