Somehow you seem to have missed the entire point of my comment, which is that there were already existing relationships based on trade and exchange that were betrayed because military subjugation was cheaper in the long run.
Where, exactly, did this occur? I suppose one could point to the United States as an example but that's an edge case: a new nation splitting off from an already industrialized nation. Japan might be cited as another example, but they notion that they didn't compromise their sovereignty is not entirely accurately. Japan had contact with Europeans since the 16th century. They didn't industrialize until Western powers used gunboat diplomacy to force favorable trade deals. Furthermore, this was in the 19th century, decades after Europe had fought the first Opium War and colonial conquests in Asia had already begun.
> but that wouldn't be enough for African nations for some reason. What exactly would those reasons be?
Africa isn't being singled out here. The rest of the world didn't industrialize just through commercial contact either.
Europe had been trading with Asia for centuries before colonization occurred, and despite that Asia did not industrialize. These regions had greater centralization, urbanization, and rates of literacy that most other regions of the world. I could flip the question around back to you: what makes you think that trade and exchange would be enough for Africa to industrialize through commercial contact when other regions of the world did not?
Your comparison with passwords is apt. In fact, it was less than a decade ago that I would sniff wifi and collect all kinds of passwords. In fact, it was so easy that a browser extension was created specifically to sniff other wifi users' Facebook passwords. That browser extension was the straw that broke the camel: since then there has been a huge push towards HTTPS.
Where does this fit into your analogy? Weakness invites exploitation, exploitation catalyses the push towards improvement. We see it everywhere: car safety, environmental regulations, Arab spring, gay rights. Yes, the colonialism _was_ necessary to get to the standard of living now seen in major African cities. As a Jew, I'll tell you that the Holocaust was a necessary step towards a modern, independent Jewish state.
That does _not_ excuse colonialism, the Holocaust, password sniffing, toxic chemical dumping, or any of the other atrocities that had to occur for the dice to fall where they are today.