Which is sad, really, because we really could use more people who can do that. In fact, I really wish that every CS program had a requirement to take an existing code base and do material work on it; it's not like anybody's going to graduate from school and then get hired to do greenfield development, so it'd be kind of nice if they were actually trained for the things that they're going to do in practice.
I just finished a Graduate diploma at a local University, a single subject had over 100 students each paying $3500 to do that subject alone yet the Uni tried to claim they didn't have the staff/resources to update that course (that was 10 hours of face to face class time) each session. I find it hard to imagine that running that one session cost even a fraction of the $350,000 paid by students to run such that there was nothing left over to fund resourcing for updating the materials.
That $350,000 goes towards staff, facilities, and research projects.
If they had the choice between funding new cutting-edge research or migrating some obscure legacy code, the new research will always win. It’s not even a hard choice.