Whereas I always take this phrase to be refering to a military kind of strength. For example, this whole article tells us that Oda Ujiharu got the nickname "weakest" because of his military incompetence. Your own examples of strength in this thread tend to be mainly martial too.
This kind of strength - the ability to force your will upon others (which is what military strength is, and also the kind of strength that 'Strong Men' dictators have), motivates the (usually incorrect) comparisons to historical empires. There are other kinds of strength - moral strength, resilience, determination, vision, etc they're just not what I think is being talked about with this phrase.
I don't know where you get 'weakness' is being described as a positive in this thread. Weakness can also mean many things, but in this context, it means being susceptible to others forcing their will onto you. It's not a good thing, but differences in strength are natural and impossible to avoid. What is a good thing is when the great mass of comparatively 'weak' people realise that together they are stronger than the tyrant.
Rather than 1984, for an appropriate comparison I'd go to the Bible:
- "God chose the weak things of the world to shame the strong."