Right now, armor doesn't have that much impact in the game. This makes thinks like polarizers, armor piercing, and armor rotting a not so effective gimmick.
I think I can nail two reasons behind this:
1. On average, armor is about an order of magnitude lower than single shot damage. Even if you constrain it to ships that are specialized in armor, it still on average a half an order of magnitude lower than average single shot damage.
2. Currently, armor cannot stop more than 80% of the incoming damage, aka, the minimum damage due to armor damage reduction is 20%. That minimum seems a bit high.
Sadly, this is not the kind of thing that can easily be fixed, but will require a major re-balance.
But to start, how about something like, reduce minimum damage due to armor to 10%. This should still be high enough to not be annoying, but low enough to make high armor values mean something. (It used to be 5%, which proved to be too low)
Across the board increase armor by a factor of 1.25, except for things that already have absurdly high armor values (raid starships, armored force fields, things like that)
Exact multiplier may need to be tweaked.
Anyone else have thoughts about this subject?