The IMA B-Rep is described as a 2.2 metre tall lumbering war machine hard-body, heavily armoured in ceramic plating... Yet can be killed by a guy armed with a TL 7 assault rifle (without using AP ammo). This thing isn't even available until TL 13.
This is not the description of something that can or should wear additional armour. You don't make tanks that require additional armour for normal usage.
Exoskeletons are described on page 26 as a form of battledress armour that is fused directly with the body to some degree. The TL 14 IMA Deep Space Exoskeleton on page 29 is also described as being heavily armoured yet has no more armour than a regular Vacc Suit. This thing has no advantage over a Vacc Suit, has a -2 Dexterity penalty, costs 2 Mcr, and is exclusive to the Imperial Marines.
If these armoured bodies were supposed to count as natural armour, then the article should have said so. The descriptions don't say any such thing, and imply otherwise.
Could you imagine a suit of Battle Dress designed for the B-Rep? The suit would give the B-Rep 18 Strength, 12 Dexterity, and armour 20. It doesn't make any sense to design a war machine that needs to wear a specially designed suit in order to carry out it's normal functions.
