We do have "sound engineers" and "special effects engineers", consistent with a vernacular use of engineering to mean "the ingenious use of technology" (made up by me).

And railroad engineers! Can't forget them! :)

One thing that makes me worry less is the restructuring of the FE exams to reflect the body of knowledge in the various fields.

I don't know anyone that took their discipline-specific FE exam instead of the general one. Way back in undergrad, it was suggested that the general exam was easier. Do you know what the advantage is of the discipline-specific FE exam?

Another interesting thing I learned is that certain fields are just title based - I believe that this means you can't represent yourself as an "Industrial Engineer" in a professional context if you aren't a PE, but there isn't a practice restriction (at least that is how I interpreted it, because I don't do either it doesn't really affect me).

That's certainly the case for systems engineering, which feels related to IE, but IE has a PE exam and systems engineering doesn't. You look at the projects that systems engineering is applied to, and they're certainly the sort of critical things (like aerospace) that you would want oversight over. I guess those in charge see the systems engineering trade association handing things fine without NCEES getting involved. Long live the industrial exemption I guess.

I'm curious to see what happens to software consultancies, and if perhaps principals are going to need a PE like you would see at other engineering firms even if they're not handling safety or mission critical projects. A PE certainly helps in qualifying as an expert witness. This point goes towards your concern over scope creep, certainly a valid one.