I have not taught any of that myself, so I will not give a full-throated defense of the practice, but I will point to something you might not have thought of.
The purpose of a lab assignment is typically to get students to understand and work with a series of concepts being taught in class. That might mean that we focus on outdated technology, if the underlying learning goal is clearer there.
When I teach students about the basics of assembly, program pointers, and stack pointers, I don't delve into x86 assembly. It's too rich, too difficult, and (most importantly) obscures too many of the details I am trying to teach them. Instead, I use 6502. No one pretends that it's even remotely modern! I'm not tricking my students into thinking that they're learning the cutting edge. But the ideas that I am trying to get them to understand are there, on the surface, in a rich (and idea-rich) enough environment that students can delve.
Similarly, when I want to teach about manual buffer overflows, fuzzing, and shellcodes, I go back to a *nix virtual machine from the early 1990s, before there were stack protections. My learning goals are best served when the activity is hard, but nevertheless approachable enough that they can have some success at it with a bit of focus and guidance.
I never have to pretend that this is cutting-edge stuff, and the students never think that it is. I content, instead, that this is an excellent environment to learn the fundamentals of what a buffer overflow attack is, and how it works in an environment that is (again) quite rich, but lacking any sort of modern stack protections. I want them to do it by hand because I want them to really understand it, so I don't want those protections.
When I teach students about processor architecture, I again head towards a fake model processor. It's not that modern processors are uninteresting! It's that they obscure the fundamental basics that I need to show them. I use a fictional processor designed by some other teachers that put the fetch-execute cycle at the forefront, and have the students implement that.
So, it could be that, as you say, the professors are simply being lazy. Alternatively, it could be that the older system has educational benefits specifically because it does not do a lot of more modern stuff that obscures the concepts that the professor is trying to get students to understand.
For more specific than that, you'd probably have to ask the teacher directly :)
