so that armor can have 50-100 times more hp than the advanced armor block.
The maximum HP a block can have is 255 iirc, due to the size of the block data. If you max out the armour though, you get something close to 25500 Estimated Hit Points (Currently Advanced armour has like 1000 EHP I believe).
There is also the problem of 2 fighters using said armour and then fighting each other, their small weapons would not be able to damage each other well, and it kinda kicks around what little we had for Anti-fighter turrets.
The problem with Armour is that it doesn't scale with size like weapons do, which is suppose to be fixed with the HP system (which comes with a shipwide armour migration system).