he bombers choice to hit an easy target - an area with a large population of families including young children was instill fear and loathing. Yet the bombers whom were instructed by a Chechan mastermind forgot one aspect - the Boston Marathon would have medical personnel present - the amount of deaths were left to a minimum. (i am not being heartless to those whom died and received debilitating injuries). Maximum casualities were not achieved. This type of destruction will come into play again till maximum casuality rates are achieved and the desired outcome is achieved - more 9/11 diminshment of American Freedoms and liberties. Look at the Worldtrade Center Bombing in 1993, 8 years later they achieved their objective on 9/11.
Muslims use significant dates in their history of the caliphate and also battles with the West, where in fact the Muslims were unsuccessful. They want those dates to be etched into into the radical jihadist mind. Maximum destruction and death will make you a martyr. If the jihadist will achieve a success, he/she will be held on high and more jihadist will become emboldened by the success.
In 1983, the Marines Barracks in Lebanon was blown up. in 1993 the World Trade center, The USS Cole, The 9 11 attacks on New York City the Pentagon and the plane that was crashed into a field in PA. The Muslim psychiatrist of Allah Akbar fame and the other list of terrorist attacks shoebomber, underwear bomber all this attacks have a purpose to inflict fear and make the American people cower to the Muslim.