I do think maps should be designed with some principles in mind;
- Avoid unnecessary diagonals. If rotating the map 45 degrees reduces the number of diagonals, please do so.
- Try to use curves that can be plotted with a compass (i.e. circles or partial circles) instead of others; this makes drawing maps a lot faster, and hand-drawn maps will look a lot better.
- Try as much as possible to make it clear whether a square can be occupied or not. If you cover a square 50%, for example with a diagonal line from corner to corner, it's quite unclear. If you shift the wall a little bit, squares will be covered 75% and 25% alternatingly, and it's clear to everyone if you can move into that square.
I think in most cases, you can achieve the visual effect of the map while also keeping to these guidelines for useability.
This map... the idea of the butterfly shape is wonderful. But it was really annoying having corridors with a width of 0.5 + 1 + 0.5 in combats, because of diagonals.