And why's that?

Mark Steyn - No other word for it but slaughter:

When your asymmetrical warfare strategy depends on gunning down schoolchildren, you're getting way more asymmetrical than you need to be. The reality is that the IRA and ETA and the ANC and any number of secessionist and nationalist movements all the way back to the American revolutionaries could have seized schoolhouses and shot all the children.

But they didn't. Because, if they had, there would have been widespread revulsion within the perpetrators' own communities. To put it at its most tactful, that doesn't seem to be an issue here.

You already know the answer.