Pietro's death in AoU never bothered me. I also don't feel like we need to bring him back. Some deaths do have to stay permanent. This can't be like comics where dying is a joke. Something like the snap, yeah there was never any expectation of being permanent. But by that same token, you can't just fake everyone's death or just bring back anyone who dies. At least, not deaths that were meant to stick. At a certain point, that will take away the illusion that death is possible. I wouldn't throw a massive fit if Quicksilver was brought back, but we're getting close to a point where no one can actually die if we keep bringing the Coulson's and Quicksilver's back.