Computer-assisted design wasn't a reality until the mid-late 1980s, and I presume the advanced modeling/design of optical systems wasn't mainstream until that time or a little later. Hence, inserting an extra 2-4 lens elements wasn't a task to take lightly. From Wikipedia, "The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by shipbuilders of the 1960s."


Likewise, affordable gyroscopes suitable for mass-production and low-power usage weren't readily available "back in the day".