I consider your average sinkside soap dish a design failure. They either have no drainage, leaving the bar to sit in a puddle of water that transforms its underside into slime, or they drain into a container, and either way you have to empty the damn thing. The notion that this thing is designed to hold soap for you, yet you must constantly attend to it by draining it into the sink, is absurd. Oughtn't good industrial design free us from this minutiae?
A far better idea is this design for a slanted soap dish pictured up top. But Jeez Louise is it ugly. It looks like the bottom half of a mouth, with two fangs and a leering tongue.
That being said, it looks like it would get the job done, at least for certain types of sinks, and one variant of this design has a suction cup on the base so it doesn't tip over. (Both are made out of plastic, not porcelain, so it's probably too light to not tip over during use.)
Where the overall the shape came from is no mystery—the form clearly follows the function (the function being self-drainage). Which begs the question: What do you do when form follows function, and the result is freaking fugly?