Maps are intrinsically vector data, and a raster graphics display back then would have been low-res, 320x240 at most, making the map (and text!) really difficult to read. And then you’d need the rasterizer itself, using precious CPU cycles and memory bandwidth to turn perfect mathematical line segments into crude pixelated approximations. And yes, the memory needed for the framebuffer was also likely an issue. The question is more, why would they ever have used a raster monitor? None of the advantages of raster were applicable, and the disadvantages were all relevant in their use case. The 100% obvious choice was vector.

All true.

> None of the advantages of raster were applicable

Colour might have been nice though.

I believe a vector CRT could be color just like a raster CRT can, using three phosphors and three electron beams (sure, technically that would’ve made the monitor a vector-raster hybrid). That would’ve raised the cost even higher, which I assume was the main reason the system was monochrome. Sure, you couldn’t easily render filled geometry with a vector display, but it wouldn’t have been anywhere near feasible with a raster monitor either given the puny hardware.

Atari's Star Wars had a colour vector display two years before the Etak was released.

I think a vector display makes it easier to rotate the map.