Ok, I understand that Auto-Armor isn't gonna be changed, but surely Manual Armor can be?

Using armor mode is a skill. That skill asymptotically approaches some theoretical maximum that we will call the 'best humanly possible value.'

Now.
Auto Armor gives you that skill level. It makes you as good as it is humanly possible to be at using armor mode.
How can that not be overpowered?

It actually makes you better than humanly possible because it skips the transition time.

I've come to accept that Auto-Armor is as it is, but Manual Armor having a transition is one of the stupidest things I've come across in this game. Some players kill others ridiculously fast. So fast that, even if you can manage to hit the Armor button in time, it still might not matter, because you won't be able to transition into Armor.

If Auto-Armor is to stay as is, then Manual Armor needs to be rid of the transition in order to get a better balance between the two.