Dont forget greyhound and sexton
Miragefla didn't forget either of those units. In fact, he pretty much went ahead and rebalanced every single out-of-meta unit to make it interesting.
However, for the purpose of such a massive patch, it might be better to have players focus a bit more on the core-tree / in-meta doctrines (which will impact balance the most).
Naturally, most players that will bother with the balance mod will flock towards the new shiny toys (I know I did, in Miragefla's mod). Having too many shiny things will detract attention from nascent balance issues (which is what the mod should be testing!), to just fooling around with the new things. For instance, we know that Miragefla's mod is fun to play. But we don't know if it is balanced; and we don't know how many strategies for each faction are viable (perhaps the current meta ones will become unviable).
Thus, I think it was a very smart decision by Relic to only include part of the Miragefla patch into the balance-mod. As long as the subset is coherent (e.g., "Trade Schrecks away, but don't forget to add Smoke and Raketen buffs"), testing the mod will not be a disaster
Once the big patch hits (or what's left of it), Relic can start integrating doctrinal non-meta units into the meta, little by little in subsequent patches. But now, it's just better to draw everyone's focus to the core army abilities.