I don't know Joe. I think I have to disagree with you on this one. Just as vehicles had a lot of their power neutured, I think it was a conscious choice to phase these pieces out especially, since there was never any models made for them.
UWZ is designed to place the focus on the infantry, with this being a skirmished based game. Not only did these artillery type pieces give the game more of a large scale battle feel but, they also threw around some very large templates. Under the new template rules in UWZ, this would be very unbalancing.
I really hope that these pieces remain as part of the history of the game and are not brought back in some unoffical suppliment.