Full coverage of the terror attacks in the Sinai here.
While I would never blame the victims for acts of terrorism, I must ask in this instance what so many Israelis were doing in the area. The government had specifically been telling citizens not to go for weeks, and even more specifically not to go over Succot. Everyone knew about the warnings -- and went anyway.
Clearly, some people assumed that because nothing had happened so far the threat was exaggerated (there were even reports, I seem to recall, that another attack in the Sinai was foiled a few weeks ago). Perhaps people also felt that there are often terror alerts in Israeli cities which usually/lately come to nothing and that that would be the case here too; the obvious difference being that there is no one to protect them overseas. However, there is no excuse for ignoring persistent and clear terror alerts, and Israelis should known this better than anyone.
I see the same thing, incidentally, in London the whole time; although the police catch people planning real and devestating terror attacks almost every month, people are completely apathetic to the threat -- precisely because of the police's success.