That’s a
whole other can of worms.
I definitely veer more towards over-protecting than under-protecting. Although my 10 year old daughter has now seen the first 6 Star Wars movies (and wasn’t traumatized—not even by Jar Jar

), that has only been a recent development. She also watched the two National Treasure movies. Those are, so far, the only PG movies she has seen (with Episode III being the lone PG-13 film).
I think it depends on the kid, too. Some kids are more sensitive to those things, and that’s okay. Personally, I’d see the fact that your child experiences sorrow at the thought of a planet full of innocent people being destroyed as a moral victory as a parent.
It’s a delicate walk, to be sure. Our children will encounter some of these things eventually, so we cannot pretend they don’t exist. But we can also—in an age appropriate way—let them know
about the existence of such things without
showing it to them. And then encourage them to make good choices.