There is an argument that other established races in the 40K should reasonably expect lists and support - Tau, Necrons, Tyranids. Thats before you think about the fringe races such as Inquisition, etc. I dont think that it can be argued that the initial intention WAS to cover a variety of not only races but variant army lists (illustrated by the development of Marine Chapters inidividually, etc).
I agree that all official GW lists are officially supported by miniatures, but if Blood Bowl had only had Orc and Human teams, and no other teams or miniatures, would the players say that was great as it was fully supported?