Sugar does more than just sweeten the flavor of bread. It absorbs water, which slows the development of gluten—in other words, it makes your bread more tender and gives it volume. Sugar is also food for yeast, helping it grow faster. It also often contributes to a nice golden crust.
So, if you want to get the best results for bread recipes, i would not recommend leaving out the sugar. The small amount of sugar that is used as food for the yeast and to create tenderness and a golden crust is not usually enough to make the bread taste too sweet.
Recipe: Pam's Country Crust Bread