Not sure why you think artillery is so defenceless?
Despite your calculations you are actually saying that, if the gunners are lucky (i.e. make their Saves) they get to maul the infantry. But IMO they should not have to be lucky to do that to infantry that walked straight into the barrels of the guns... In any case, I saw my unlikely scenario happen several times.
There´s another weird scenario as well that you get with the standard rules. My opponent walks his infantry unit within range of my infantry unit. He then shoots at me. I can´t do anything since he does not traverse my front. Then it´s my turn and I charge him. He then shoots me again with Closing fire. So despite the fact that he is covering the greater distance, he gets to shoot at me twice and I don´t get off a shot. I just think that this is odd.
With my version, he would walk up to me and get shot by me. I would then move and Charge. He would get to shoot at me (regardless of a Charge, actually) and in case of a Charge we would engage in HtH combat. Sounds more realistic to me and you lose all the discussions about traversing fire, which you do not need anymore.
But, as I said before, I need not make any converts here. It is just the way I like the game better. Feel free to disagree or apply your own preferences. This is, after all, in the flavour of the game.