Some models of LaserWriter also had an undocumented PostScript command which would print a La Costeña order form for you to fax in. I always appreciate super-obscure Easter Eggs like that.
That Easter egg is apparently so obscure that your comment is the only thing about it on Google:
Sorry I'm late seeing your comment, but I'll tell you what I know for posterity. I heard the story third-hand: a prior manager of mine, Mark "The Red" Harlan (of Clarus the dogcow fame), used to be a DTS manager at Apple back in the late 80's/early 90's. He also hosted a MC'd at WWDC each year called "Stump the Experts," where the audience got to challenge a panel of Apple engineers with the most obscure questions possible. One audience member asked about this PostScript command, and one of the engineers admitted to the fax-in burrito order form. Sorry I don't remember the engineer's name or which WWDC year, but I'll ping Mark.
Kurzweil Music Systems produced the 150 additive synthesizer around the same time that also used a 12 MHz 68k. Do you know if this faster variant was encumbered in some way that made it less suitable for use in a "general purpose" computer, or was it simply a cost consideration?
I'm not sure how you think it would be encumbered, but from the Wikipedia page, my guess is it was mostly cost. The faster variants (like 12 Mhz) were only available later, and I would guess that was due to improved production processes and binning that enabled them.