Interesting thought, but I would imagine it would be a pain in the neck to make an angled humbucker - one of the bobbins would need to be shifted forward a little bit on the
base plate to compensate for the angle in order to keep the pole pieces relatively well aligned, which means that you wouldn't get such a neat job when taping the coils etc. You'd also need to manufacture custom base plates or redrill them to compensate for the difference is screw positioning. Maybe there's a niche market there waiting to be exploited! ;o) It would sure be cool to make humbuckers with more bite without resorting to winding one of the coils hotter than the other though.
Cheers,
Dave