The “all hook and no I” introduction has paragraph upon paragraph (or even page upon page) describing how other scholars have viewed the issue the article addresses with little indication of how the author’s thesis fits into this conversation.
Conversely, “the no hook and all I” introduction immediately launches into the author’s argument without establishing the current scholarly conversation that makes it meaningful.
You might opt for the all-I intro because you want to give your readers credit for knowing a lot about the relevant scholarly conversation rather than rehearsing points you believe they are already familiar with.
Another honorable justification, but one that often has the unfortunate effect of suggesting that you are actually not familiar with what other scholars have said.
We also want to note that using the hook and an I approach is ultimately less a matter of sheer quantity -- X number of sentences or paragraphs to others, and Y number to your ideas -- than of argumentative quality.
Good introductions do not just repeat what other scholars have said; they analyze it and find an opening in it for their contribution.
You then proceed to provide the relevant context for that thesis.
For examples, see Brian Mc Hale, “Beginning to Think About Narrative in Poetry” and Susan Wolf, “Moral Saints.” The Storytelling Strategy.
The first involves a general approach to the challenge, and the second builds on it with more specific advice.
First, think of your introduction as needing both “a hook and an I,” a precept that becomes clearer when you think of introductions that have only one of those components.