Why has the Nexus 8 speed hub gear not caught on?

[Artstu]

In summary, hub-gears are great for the girls that want to have a liesurly ride down to the supermarket without getting their dresses caught in the gears or chain.

yea yea yea

 

[Benjahmin]

I think it comes down to expense and complexity.
If something goes wrong with my deraileur, I fix it in the shed with readily available parts. having set mine up I haven't had to touch it in about 3k miles. This despite stories of cable stretch, bent hangers etc.
I admire the engineering of hubs but, really, they are far beyond KISS.