Do you really want to side in leyline of the void against decks playing wrenn and six, snapcaster, dreadhorde arcanist and such things ?

As you said, games tipically go long, so siding in 4 totally uncastable cards that do nothing except if you have them in your opener doesn't seem like a very good idea.

It is true though that exiling graveyards right now seems absolutely bonkers. I was thinking that a build with 2-4 rest in peace main, one helm main and one helm side could be very good right now. It would be a very different deck though because we could not run welder/engineer and probably we should also cut copter then.