The reason for guitar pickups being that way is that guitars and guitarists are often stuck in the past. Everythng has to be the way it was 50 years ago. Bass players are more open minded when it comes to something different. So a lot of the innovations come on bass, while guitars are still stuck with just Fender or Gibson style pickups, even if they aren't Fenders or Gibsons. I found a lot of irony when Fender started using humbuckers on some guitars, and Gibson even had a few with single coils. That would be like Ford using GM parts and vice versa.
A few guitar makers are using proprietary shapes, like PRS. I think thats a good thing. They can make them work better, and fit the stye of the guitar better. It's very limiting to try and do something original with pickups, and you are stuck with a few common shapes on guitar. And then the mounting method for Gibson style humbuckers is archaic and doesn't work well. The long leg humbuckers wobble and won't angle properly to match the strings. A few companies like Carvin and Schaller, use three or four screws, and that should be the standard. You can set the angle of the pickup that way.
But now even bass players are starting to get in the vintage fad and everything has to be a Jazz bass with single coils. Things were not better back then... bass amps were under powered, and the choices in strings was limited. We have moved forward where bass is now up front in the music and taken seriously as a instrument. There's no need to stay in the past. It might seem cool looking back on it, but it wasn't.
[end of rant]