I watched this programme called 'Educating Yorkshire' and in one of the episodes there was this boy with a severe stammer who was practising for his English speaking exam and I just cried because he was struggling so much. Then, with the help of his teacher, he overcame it by listening to music with earphones and he spoke so well and he made a speech in assembly and it was all incredibly moving. I would recommend anyone to watch that series. So yes, to answer your question. I think its because we can empathise so much with them.