Why is the man made to be unappealing in "War" by Pirandello?
I assume that you are talking about the fat man who talks about how his son was proud to die for his country...
I imagine that the author makes that man unappealing as a way of commenting on his ideas. The ideas that the man is expressing are clearly opposed to the ideas that the author wants to convey through the story as a whole. So, by making the man all fat and not very pleasant to look at, he is kind of telling us that the man's ideas are unpleasant as well.
The father whose son is dead is made to seem unappealing at first because he initially is the spokesperson for an unappealing view of warfare and of the need for deaths during a time of war. In effect, he is seemingly the least worthy of the characters on the train, and the most "brainwashed." But at the story’s end, once the question about the reality of death is posed for him, he changes, and the final stress in "War" is upon his personal grief and the irreparable loss that he has suffered. This is a common theme in anti-war stories.