As I understand it, Roy Thomas was going to add a new character to The Avengers, either the Golden Age Vision or a character based on it, when Stan Lee instructed him that any new character must be an android. This would explain why the original design of the modern day Vision is more other-worldly in design that futuristic or robotic.

https://www.deviantart.com/nick-perks/art/The-Golden-Age-Vision-870643936