Officials in the defense establishment believe Hamas views the prospect of marching civilians over the fence as a win-win situation. If some of the thousands of people Hamas brings to the border manage to penetrate Israel despite the IDF troops in the area, then it will have once again broken the ring of economic isolation around Gaza.
If the IDF halts the marchers’ advance with violent means, killing demonstrators, then Hamas will have demonstrated Israeli brutality toward the masses struggling to carve out a living in Gaza. http://www.haaretz.com/hasen/spages/957776.html

See also:
http://ap.google.com/article/ALeqM5jD4YSkDPlclqd9dHvg2f0Ij18zEgD8V1AM480
http://www.ynetnews.com/articles/1,7340,L-3511002,00.html