Why do you need a reason? You have graduated, you moved on with your life, and you are out of the loop. If it's "required" and you don't have it, it could certainly be a problem, but, if the letter isn't going to help you, you already have a problem. At most schools, though, whether they are preferred or required, people on SDN have reported success without them.
Seriously, though, I'd ask for an appointment with the person in charge of pre-med advising and ask for an honest assessment. You might not realize how good your letter might be, or how whatever stratification your committee performs will impact you. Hopefully, they'll be honest with you. If you go back to the general advice
@Goro and
@gonnif love to repeat over and over and over, we all start out rejected and schools are just looking for reasons to knock out 80%+ of us in order to make their jobs more manageable. I am absolutely not motivated to help them at all in that pursuit.
🙂
If a committee letter is going to put you in the bottom half of applicants from your school (or, maybe, even outside the top 25%), I don't see how it would help, unless you have some powerful hook that would cause a school to read the committee letter and still want to meet you, and I'd just as soon take my chances without it. Keep in mind, I doubt you'll ever get to see the actual letter (unless you don't sign the waiver, which creates a whole other set of problems), so the closest you'll come to knowing whether or not it is decent will be if your advisor is willing to share how they think yours will shake out based on what they know about you.