"I definitely want someone to be able to modify, fork, and publish better versions of this code. Do I also want them to be able to commercially license their derivatives?"
On one hand, this code was contributed to the public commons and it'd be sleazy for Amazon to come along, improve it, and license it. It seems unfair, and the spectre of giving free labor to innovation-killing, rich entities discourages me from contributing. A GPL license takes care of that concern, and provides a much-needed codification of fairness.
On the other hand, giving people an MIT license and saying "You can do whatever you want! Go nuts! Innovate!" is a boon to creativity. If some startup took my weekend project and made $1 billion off of it, good for them! That's the innovation that open-source is meant to encourage!
When the article mentioned that coders are confused, it hit the nail on the head. We're confused individually and collectively; emotionally and conceptually; theoretically and concretely.
We're looking for a simple answer to the question "Which option do I select from the GitHub license dropdown so I can get back to making value" when there's no simple answer to be found.