1) That isn't really true. For instance, today, there isn't two Northern districts. There is a Northeastern, Western, and Southern district. Before that, there was a Northeastern, Northwestern, Southwestern, and Southeastern districts. Before that, there was two Eastern districts to the North and South, a South Central district, a Southern Western/West-Central district, and a North Western/North Central district.
2) In the previous restructurings, the Southern districts were restructured to be East-West rather than North-South. I don't see how you can produce a compelling reason to claim what was good for the South is unacceptable for the North.
Bottom line, two districts cover the Northern part of the state regardless of containing other portion. It's a partisan gerrymander, pure and simple, what is the point in arguing that it is not?