SPACE MARINES ARE ALREADY A WALKING LIGHT VEHICLE IN POWER ARMOR… SO WHY PUT THEM IN ANOTHER ARMORED BOX?

SPACE MARINES: ALREADY SEALED IN CERAMITE THAT COUNTS AS A LIGHT VEHICLE; IMPERIUM: "BETTER WRAP THEM IN ANOTHER ARMOR BOX" — SO A LUCKY PLASMA/LASCANNON SHOT CRASHES THE CHASSIS INSTEAD OF JUST HITTING TWO VERY ANGRY MARINES