A disadvantage of WED is its incapability to do anything without blocks or terrain. E.g. it is really hard to build a street (that is not just a plane), because it is nearly impossible to move the blocks in the perfect position, so no "steps" or gaps are in the street (it is just not possible to get the edges of the blocks perfectly together, the snap-to-grid-feature helps only when using nearly non-rotated blocks). Triangles or a snap-block-edge-to-block-edge feature would fix that and would make it possible to make a more complex floor out of more than one single block without gaps or steps.