I think you’re overthinking this, e.g., Zemax’s optimization isn’t that different than the ray-tracing presented in this book. The sophistication truly comes from the users.

Yeah, perhaps.

But the heavy-hitters in this field all seem to have very old-timey UI's and out-of-this-world pricing.

Meanwhile, raytracing for computer graphics on GPU's is soooo performant-- it makes me wonder how much work needs to be done to make the equivalent of KiCAD for optical design.