Okay, here's the bottom line.
Because of how the dodge mechanics were changed and function, the drop was necessary to hold combat designs within intended design. When you refine armors, you gain dodge per piece of equipment, as opposed to the weapon's single point of accuracy increase. The difference is, there are fairly standard passives within each skill tree that boosts accuracy, but not dodge, not for all classes. Other considerations to how dodge and accuracy generate between all classes and core mechanics now, was cause for reducing the heavy armors' dodge rating further.
The soldier is not a class intended to have a natural dodging ability. The Spear Champion has a passive that pushes their ability to dodge to a rate that can increase damage mitigation well against lower to mid accuracy type classes, but they are not intended to be able to compete with actual dodge based classes.
Muse armors were boosted, because of as stated above, physical damage reduction is a significantly higher damage type source than magic and with recent balances, their damage mitigation ability was reduced. To give some back, and also under the argument that their armor is the lightest and easiest to move in, their dodge was increased.