If Bruce Wayne's parents came back from the dead, his trauma would not heal and disappear.
On a practical character level? No, they wouldn't. On a thematic level? It would absolutely be a horrible distortion of one of the fundamental core concepts of the mythos. *Bruce* might still be broken, sure, if he works the way a person does, but the literary legitimacy of his brokenness would most assuredly be gone. You can't possibly really believe that the Batman franchise is still the Batman franchise if Thomas and Martha are hanging out in the Manor drinking tea with Alfred while Bruce does his thing.
So I don't see this as something that is permanently changing or affecting the theme and status quo of Wonder Woman.
And now you're missing the three years argument. Bruce bought a gun in Murderer/Fugitive, yes. He contemplated it in a very serious way that directly addressed the thematic clash between it and him as a hero.
He didn't just go out there and use it for three years straight like there wasn't a thing wrong with it, and then be like, "hmn, what if I start using a gun, and how will that affect me?"
Which is what we're seeing here with Diana, effectively. "Let's have Diana not be Diana for like a zillion issues, and then let's make her Diana again for like, one, and then make her not Diana again because wouldn't that be fun to explore."
No. No, we've been exploring that. It's time for it to end.