My houses are boxes too, because I can't make roofs. Sometimes I get creative and add balconies and not so straight borders but basically they're all boxes. Most of my lots are 1x1, 1x2, 2x1 or 2x2 for big community lots, so I like to keep it simple. Also, in the zombie apocalypse, sims can't be picky with their houses design. Some even live in metal containers or abandonded hangars.