Going from 2 to 4 legs doubles the amount of actuators required and substantially increases power consumption since you must move more mass, going to 6 compounds the problem further. In a future where we have more dense power storage and better (and cheaper!) motors, you probably will see robots with more legs. But for now, the most efficient solutions are bipedal.

Especially because this thing is already $8k, I imagine they have already done some substantial price optimization.

They make robot dogs, e.g. famously Boston Dynamics but many others as well. And 6 is probably overkill for price/performance increase incremental to 4. Wheels are still much more practical and you can use them as feet in hybrid designs to be able to step over obstacles but still more agile than comparable bi/quadrupeds

Entomophobia/arachnophobia is far too common for giant bug-like robots in folks' bedrooms.