Yeah, that's the thing with silly examples (like my Mandelbrot program). For real code, I frequently need to write low level loops which aren't easily expressed as parallel operations. If numpy doesn't have it, or if you can't figure out how to parallelize it, you're screwed.

Moreover, for some very common things in signal processing, like working with evens/odds or left/right parts of an array, the parallel numpy operation will create lots of temporary arrays and copies.

And for what it's worth, your version of mandel should work with PyPy. So you can have your cake and eat it too.

EDIT: I should add the reason my code is "strange" is because I wrote it so I could do a one-to-one comparison with other languages which don't have builtin complex numbers. Maybe I should've cleaned that up before posting.