The reason it is so low res is actually more interesting than simple aesthetic choice. Think about the sensor(or eye) needed to view a 3d scene, it is 2d right. So this is a 3d sensor(voxels) for a simulated 4d camera. and then we are looking at the 3d sensor. (with our 2d sensor(eyes)), it's sensor inception.

So it is as low res as it is because it is a bunch of voxels simulating a 4d camera.

The dev put out an interesting video on the topic.