Here is just my thoughts on the very much argued and discussed cover issue.
I think that cover should be done the following way. "If you can draw a straight line from the firing MODEL to the enemy UNIT without crossing any intervening terrain, than that unit is not in cover to that MODEL" or an alternative way of saying this would be "If when you draw a straight line from the firing MODEL to an enemy UNIT, if that line must cross any terrain feature, than the enemy UNIT counts has having cover from that MODEL". Yes this would mean that sometimes a unit would have cover from only some models in a firing squad, so you would need to roll the shooting from models that are not going into cover separate from models shooting that are going into cover, but I don't think this would be overly complicated that it would hurt GW's need to keep the game simple. The other thing I would do is have three classes of units in relation to cover. Infantry/Bikes/Calvary would always have cover from terrain. Vehicle/Monsters/Chariots would only get cover from terrain that is agreed before the battle as providing cover the vehicles. I would give examples like Walls/Obstacles that are taller than an infantry model, Ruins, Forests, etc. Finally, I would have a keyword for what were once "super heavy vehicles" (if they don't, I don't know if they do) and super heavy vehicles would never get cover. Even if they are like 90% obscured, that is still a hell of a lot of model still showing from the perspective of an infantry model. Also it simplifies the issue of such a large model being blocked by a very small piece of terrain. Again I don't think that any of this would add a level of complexity that would be unacceptable for 8th edition, and it greatly improves cover (which would help with the alpha strike issue) and gets rid of any "is it or isn't it 50% obscured" and makes all cover issues basically objective. And of course you could have terrain with its own rules like craters you have to be in the crater to get cover etc. This is must my thoughts on the matter feel free to tear it apart.