I think the misunderstanding comes from the difference between a framework crafted for McKinsey vs. a framework created for other consulting interviews.
At the core, McKinsey wants to see creative ideas communicated in a structured manner, the more exhaustive the better. Your goal should be to come up with a tailored and creative answer that fits the question. Think of it almost like a mini case within the whole case.
The framework should - broadly speaking - follow these three characteristics:
As I understand from your question and the reaction of the interviewer, you did not qualify your answers enough and create good enough insights. It is important to go really deep with your explanations about each branch of the tree and discuss their merit in your structure, the more concrete ideas and the more actionable, the better.
Rushing through the structure in a McKinsey interview is never a good idea.
Since you say you have been told to present the framework swiftly (from who?!) and I think that is where the disconnect comes in. In a McKinsey interview, you can take up to 6-8 minutes to present your structure, your qualification, and hypotheses. This is due to the interviewer-led format that McK employs. The interviewer will only ask 'what else' if you
- haven't gone broad or deep enough
- did not explain your ideas well enough for them to stand out (again, you have time here)
The firm wants to see exhaustive and creative approaches to specific problems, which more often than not do not fit into the classic case interview frameworks that were en vogue 10 years ago...
Again, this only applies if everything you say
- adds value to the problem analysis
- is MECE
- is well qualified
- includes a detailed discussion of your hypotheses at the end
The difference in format and way of answering a question is the reason why I recommend preparing very differently for McK interviews vs. other consultancies.