Why not? It is quite natural to want your war enemies to die, and for the whole country (both soldiers and civilians) to celebrate destruction of enemy troops.
Think about the tweets and newspaper articles about the successful murder of Osama bin Laden, for example - it's the same concept.
The rule of law is important. Tit-for-tat exchanges like the ones that Israel and Palestine are engaging in solve nothing. It descends into monkey hindbrain us-against-them.
Another very similar scenario recently was Northern Ireland. That didn't get solved by the UK grinding Ireland into the ground or posting inflammatory things in the news - it was solved by both sides showing restraint and good will.
Currently neither Israel or Palestine are showing anything of the sort, but as the larger, more powerful party (eg. I doubt Palestinans have bunkers), it's up to Israel to show some restraint... but they aren't, they're still posturing about how tough they are.