Once someone asked Bob Taylor about Brazilian Rosewood (and this is 8-10 years ago when it was more widely available). Specially, why do we have to order a Presentation Series to get BRW? Why not just make an unadorned version available for less $$$$? He replied something to the effect of, "If you want my Brazilian Rosewood, I'm gonna sell you everything else I got with it!" I hope I'm not extrapolating this too far, but I think Taylor reserves certain "premium" features for more expensive guitars. Example: if you want a 1 3/4" nut you have to get at least a 300 series. Taylor doesn't want to undersell itself. Let's pretend for a moment that they offered a 100- or 200-series 12-string guitar. It'd totally eat into sales of their more expensive models. That's the best explanation I have of why the 100- and 200- series are limited to very common body shapes and features.
The second explanation I can think of is that a smaller Grand Concert sized guitar would be harder to pull off well using laminate woods.
And finally, I would expect Taylor to not think they could sell enough of these to justify the expense in tooling, marketing, etc.