No, I don't think it's a good idea, for reasons that vary with the student's status.
Current students: by releasing information about a student's work in progress, you make it easier for some other researcher to pick up the same project, and complete and publish it before your student ("scooping" them). This will make it more difficult, or impossible, for your student to publish their work, as it will no longer be novel - a potentially serious career impediment. Even experienced researchers tend to avoid publicly discussing their work before it is ready to publish, and for grad students the risk is greater, as they probably work more slowly than the average researcher and are less likely to win a race.
Former students who graduated: the provisional report is redundant, as a more complete and polished version of the same information is in their dissertation. They would probably prefer that this higher-quality version be the only one publicly available.
Former students who did not graduate: would probably prefer not to publicize the fact that they were a student in your department but did not receive a degree.
In principle, if a student is aware of these issues and freely consents, without pressure from you, to posting the preliminary report, it might be okay. But it's still questionable in my view, as a graduate student may not have enough experience in academia to fully comprehend the issues involved and accurately evaluate the risks. I'd err on the side of paternalism and not even suggest it.
I think it would be okay to make the reports accessible within your department, so that faculty know what students are working on, and so that students currently writing such reports have access to examples. But I would not share them with the outside world.