I've never heard that it was an obligation, mandatory, or even expected to donate. How many MU football players donate back annually? I am guessing that it is less than 10%. I am guessing that is the same number for MU baseball.
I don't think there is anything wrong with no donating back. If I gave $XXXX money each year to the program, I wouldn't be bothered if former teammates didn't give back.
By sitting quietly and not voicing displeasure, it would be a disservice to the program. That's a sign of apathy which is the worst thing an organization can have from its stakeholders.
It's why people get annoyed with you from your stances on programs that are not doing well. By refusing to acknowledge, voice displeasure, and act on a bad situation, it is accepting the failure. It doesn't make you less of a fan. If your child comes home with a report card with a bunch of Ds on it, you aren't going to congratulate them, blame it on all of their teachers, or make excuses. You will continue to encourage your child and help them, but you will also tell them it is unacceptable, demand change, and not continue to promote things that are leading to all of those Ds.
I don't feel that I am even mildly wrong about not donating to the program other than a $500 brick.