Two themes seem to dominate Commencement speeches. One is shameless self-advertising by people in government, or in related organizations supported by the taxpayers or donors, saying how nobler it is to be in "public service" than working in business or other "selfish" activities.
In other words, the message is that it is morally superior to be in organizations consuming output produced by others than to be in organizations which produce that output. Moreover, being morally one-up is where it's at.
The second theme of many Commencement speakers, besides flattering themselves that they are in morally superior careers, is to flatter the graduates that they are now equipped to go out into the world as "leaders" who can prescribe how other people should live.
In other words, young people, who in most cases have never had either the sobering responsibility and experience of being self-supporting adults, are to tell other people — who have had that responsibility and that experience for years — how they should live their lives.
In so far as the graduates go into "public service" in government, whether as bureaucrats or as aides to politicians or judges, they are to help order other people around...Ordering people around--that's nirvana for doctrinaire "social justice" types, whatever their age.