The war between the two major sects in Islam is not really a subject of interest to American journalists and not to many foreign journalists either. The first problem is that the material they'd have to learn is too weighty and too intricate. The second is that sects almost always complicate a dispatch. So better stay with the old categories.
But the fear of the Shi'a among Sunnis and tremors among the Shi'a about Sunnis constitute the shaky underbelly of Arab society. It is true in Lebanon, Syria, a few of the emirates and other princely dominions. It is true in Iraq and in Saudi Arabia where the phobia is not only about the Shiites themselves but their sponsorship by the non-Arab clerisy in Iran. The revolt against the ayatollahs has intensified the anxieties of the Sunnis in Araby in two ways.
The first is that it was a popular revolt unlike any launched in the Arab world ever. Moreover, it was watched with some envy by Arab secularists and dissidents. The second was the swift brutality with which it was tamed by the Shi'a regime. Either way, it was an awful precedent for Arab rulers of everywhere.
See this analysis from MEMRI about Saudi Arabia's reluctance to welcome Iraq's Shi'ite leadership.