So, this happened. TL;DR: yet another repetition of the same cycle of violence. [Can't guarantee link may not have been changed since writing this.]
The puzzlement comes from an overly narrow focus on a distorted narrative and interpretation of the situation.
Put that way, yes, it really sucks to have rockets randomly landing in your backyard and you can't argue with that. But that completely ignores the full spectrum of issues. Why are the rockets landing in the first place? "They are a hateful people." That is a non-answer: people are made to be hateful, not born that way. Furthermore, equating all Palestinians with Hamas or ascribing a desire to destroy Israel to all of them (when they really just want to live normal lives like the rest of us) is an easy - yet disingenuous - way to justify demonizing the entire population (and hence treating them as less than human). To obtain clarity on the issue, then, we need to look at the other side:
How about if said people were forced out of their Toronto homes they were living in to begin with (it's not simply "a bunch of people moved into Kitchener"), rounded up into a small and rather shabby town elsewhere (i.e., Kitchener - no offence to Kitchener, just going with the already-established metaphor) that is completely enclosed with fences, can't get out, have their water or power cut arbitrarily whenever Toronto feels like it, and are subjected to having their homes raided and people arrested whenever someone in Toronto even whispers that Kitchener is up to no good. Small wonder, then, that the constant humiliation doesn't cause some of the Kitchener folks to start lobbing rocks into Toronto. Then, to make matters worse, if a rock happens to land in Toronto and crack some pavement somewhere, Toronto swoops in and turns Kitchener into rubble - a massively disproportionate punitive action.
I think everyone can agree that no resolution will come from continuing to retaliate - on either side. But by using the "rockets landing in your backyard" narrative, the weight of the responsibility is sneakily entirely shifted to the Palestinians when really, the sheer unnecessary suffering of their entire populace there makes it clear that the side in the conflict with far more power (military, political, and economic), that has indeed arguably played a dominant role in setting up the entire scenario in the first place, has a much greater responsibility (and greater ultimate moral cost) for short-circuiting the endless cycle of reprisals.
For starters, we have to stop spreading, and listening to, such trivializing narratives as "rockets landing in your backyard", pretending that they exist in a vacuum, separate from the full context, and start to actually discuss what is happening in terms of the human cost - on both sides. And that's just to get a fair discussion going, let alone make any dent whatsoever in resolving the crisis.