In a balanced diet a large part of the calories (55-60%) should come from carbohydrates, in the form of starch and, to a lesser extent, of simple sugars (e.g. fruit). So bread, which on average contains over 50% starch, is a nutritionally important food, that can integrate or take the place of pasta, rice or other cereals in the diet.
Generally people on a slimming diet tend to cut out bread from their diet. But this is not a wise move, as an excessive reduction of carbohydrates has several unwanted effects. A 50g sandwich has about 140 calories, a perfectly acceptable quantity even for people who are dieting to lose weight. It is worth noting that it is not nutritionally correct to eat breadsticks or crackers instead of bread, as these contain less water than bread and therefore more calories for the same weight.
Another preconception that should be discredited is that bread is not easy to digest. It is rich in starch, which is easily digestible; it is also partly broken down by the action of the yeast and the cooking, which makes it lighter.