Actually, Hebron, Tibererias and Safad, in the Holy Land, are sacred to Jews along with Jerusalem. Also, European sites associated with the Holocaust are so emotive to the Jewish community that they deny the right of other religions to be represented there (eg the outrage over the Carmelite convent at Autzwitz), or wish them to remain forever as memorials.
Christians have plenty of holy cities! Come on people - in Europe and the old world, that has always been the case. Rome, Loretto, Canterbury, Lourdes, Fatima, Paray le Monial, Avila, Chartres ... that is just the beginning of a list of hundreds of cities which have the character of shrines and pilgrimage sites.
I agree with nuconvert's point that the media should stop using the term, as most of these places in Iraq are only of significance to Shias (just as most of the European sites above are holy only to Catholics.) Southern Iraq is where the founding events of their particular sect took place, and most of the holy places are where their tombs are.
It is easy enough to make the distinction - Basra, Nasiriyeh, etc are not holy cities, whereas Karbela, Najaf, Samarra, etc are.
There are no holy cities in the USA, which is probably why Americans find the whole concept so irritating.