I'm afraid you are mistaken.  I have read the letter multiple times and I would suspect that most in this thread have too; given the informed commentary and the ease of reading the letter from the Cardinals. To make it quite plain... Here is the passage directly from the explanatory note in the letter"

Dubia are formal questions brought before the Pope and to the Congregation for the Doctrine of the Faith asking for clarifications on particular issues concerning doctrine or practice.
What is peculiar about these inquiries is that they are worded in a way that requires a “Yes” or “No” answer, without theological argumentation. This way of addressing the Apostolic See is not an invention of our own; it is an age-old practice.

You're right that the four Cardinals are better informed than me.  However, they are a tiny minority.  Only four of a college of over 120?  I personally would not edify their objections and am happy the Pope hasn't. The lust for certainty is troubling to many.