The issue with your simple drawings is an assumption that the seating levels between East, west and North remain the same height. (Elevation not section)
The new plans for the asymmetric stand have a much higher roof line than East & west and the gradient of seating is less acute (Resulting in a step down, at adjoining East and west sections - no blocked view) There are discussions at the moment regarding corporate capacity and the total removal of boxes and high yield seating in the north stand. This can be negated commercially as there are draft plans for a supplementary (circa 5k capacity) indoor arena directly behind the North Stand, but this is dependant on timing requirements from the club.
This is also brought about by the total estimated cost / time allowances needed to replace the existing roof to make the stadium a full bowl and the realisation that an asymmetric stadium isn't a bad thing for overall cost, atmosphere and astetics