I’m not sure I agree… Even before the 2e version there was still some basic cohesion with the six limbs. The only real exceptions to this were the squigs.

By the time 2e came along, squigs were gone (along with zoats 😢) but the cohesion was increased even further - everything now had the Tyranid Warrior style exoskeletons, six limbs, teeth and shells. They looked like they shared a fundamental biology

I realise that the Armorcast models are based off the simplified cartoonier epic versions. I think the main issue is I didn’t like them to start with either 😑