[eesmith]

> Having a surplus of limbs is contraindicated for large organisms

Having a large brain is also expensive to build. It's always a questions of trade-offs.

I can easily imagine how a hexapod like a centaur (four legs and two arms) can combine the speed of a horse and dexterity of a human and make up for the metabolic overhead.

> 4. You need appendages for manipulating tools, and voices to debate and share ideas.

You don't need sound. Sign language exists even in humans.

That wouldn't even require large appendages. The "talking" could be done by photophores, or 1cm long flexible vermiform appendages, or controlling the pattern of fur movement.