Erm. You realize that splitting the station up across z-levels makes having a single dedicated engineering section rather pointless, right?
Why is that? Engineers don't have some sort of magical implant/disease that prevents them from using shuttles. And it makes engineering much less boring.
I'm not talking about engineers, but about
Engineering. The current Engineering section is built almost entirely around the Singularity Engine. You can't, to my knowledge, transfer power from a central singularity across z-levels, so you either lose the singularities entirely and run each station segment entirely on solar arrays, or you have a singularity engine on every station, meaning you have an engineering section on every station z-level, and again, not a single dedicated engineering section.
The same goes for atmospherics, you'd need a separate section for each z-level. And... and that's something of a nightmare. I mean, have you *seen* atmospherics? O_o
For the same reason splitting engineering off onto its own z-level doesn't make any sense, as without the singulo Engineering is just a glorified closet. Admittedly, I wouldn't mind having a vast empty z-level on which to build mega-projects, but it'll be even harder to justify taking the time for such projects with having to maintain multiple substations, rather than a single station.
I've never really liked spess law as written because I've found it too lenient. And what space laws says and how admins (on TG) evaluate how it is executed are different things, as well.
There's a reason for that though. It's a game, and sitting in a brig is boring. So is being dead.