Yes, 'simple hack' is definitely one reason. But there are a couple of others:
- The drawing is sent to the Arduino as a block, then drawn, so it has to fit in the Arduino's RAM. More complex drawings would require streaming the data during the drawing. That's totally possible, but it is more work.
- We quite liked the way these severely-simplified sketches came out. Because the edge-finding and vector-simplifying code is quite stupid, the best pictures tend to be the simplest ones, and doing more lines might well just make the picture more noisy.
- The drawing is sent to the Arduino as a block, then drawn, so it has to fit in the Arduino's RAM. More complex drawings would require streaming the data during the drawing. That's totally possible, but it is more work.
- We quite liked the way these severely-simplified sketches came out. Because the edge-finding and vector-simplifying code is quite stupid, the best pictures tend to be the simplest ones, and doing more lines might well just make the picture more noisy.