On some situations the people can be lured by electoral promises that the elected body has no will to fulfill, Hamas however is a long known radical faction, hardly you can say those 51% were voting by mistake, by ignorance yes.
I wouldn't say it was a mistake either.. just pointing out that not everyone is guilty because of the actions of a stupid few.
I really doubt many people in Gaza had much of a choice when they had guns pointed at them.
take Egypt for example.. it was quite easy to vote the muslim brotherhood into power.
it was quite difficult to vote them out.
take Isreal as another example... there are actually people in Isreal who are protesting against the hard line actions of the IDF but they don't get much coverage on TV. I wouldn't blame them at all for anything the IDF does. They are the smart, practical and compassionate Isrealis.
I really don't think the actions of the IDF will do anything to weaken the political power of Hamas or weaken their resolve to keep attacking Isreal.. that's why I see it as a pointless waste of life.
given time, Hamas could have been overthrown relatively peacefully just like the Muslim brotherhood was in Egypt.. but now I think that chance is lost and things could get a whole lot worse if black flags start appearing in Gaza.