Advantages of having a farm
The main advantage is liquidity: a farm bring more liquidity for the farmed pair. Lack of liquidity was an actual problem for SIDX, as it's a low cap token.
Another advantage: SmartIndex managed portfolio holds some SIDX/BCH liquidity. After proposal #11 approval, this farm will bring more value to the portfolio: rewards will be swapped for SIDX/BCH LP token and added again to farm. This allows money to flow into the portfolio.