I always thought the bio mechanical aspects to the Alien design was that added element that set it apart. Sure the lack of eyes, inner mouth were also signature features and creepy but the bio mechanical overarching element made it less of a schlocky B movie creature in my head.
I understand that the Prometheus/Covenant storyline explains the fleshier designs, but it just doesn't do it for me. Same as the newborn went too fleshy and trying to be too different.