The crackdown might breed terrorism. In the eyes of the generals, that's not necessarily a bad thing.
There were other ways of dealing with the camping-out protestors in Cairo. The ministry of interior had even talked about other ways—about some combination of tear gas and leaving open an exit route so the protestors could disperse. And surely it must have occurred to the Egyptian generals that the action they in the end took, just like the event in Tiananmen Square in 1989 that this week's event so readily evokes, would leave a lasting bloodstain on their legacy. The casualty total of what happened in Cairo Wednesday is uncertain, just as the toll of what happened in Tiananmen Square still is, but it is possible the numbers are of similar orders of magnitude.