Not all the growth in admin costs are bloat. In fact, a lot (and maybe most) of them are not. The Dept of Ed has raised all sorts of reporting requirements over the past 30 years. Who collects that information (that was never collected before), compiles it, creates the report, files the report, and then answers questions about it? Yep - administrators. Sorry about that.
IT services are also a huge, and new cost of administration. 35 years ago the typical campus computer network probably consisted of a few dozen computers and a few dozen more terminals. Fast forward to today, and the computer network is wireless and capable of attaching 2-3 devices per person on campus (students, professors, admin people, visitors). Yeah, that's a bit more expensive.
Classroom services is another one. 35 years ago you could hire a high school drop out that knew how to change a bulb in a transparency or slide projector and run a film projector. Today you need someone who can troubleshoot attaching video and audio from an iOS, Android, Windows or Linux laptop, tablet, or phone to the classroom A/V system - odds are that support person is going to cost more than someone who knows how to change a light bulb.
Not all admin costs are bloat...