I've a theory that a more interesting neck pickup would sod up the tonal balance it creates with the bridge pickup, and I definitely dont want that to happen. Effectively I'm using the two pickups to make a one sound instrument and that's fine by me. The combination of strings and pickups as they are seemingly allows me to get a wide range of tone and dynamics from varying my touch, like on a piano.
My P with a Dimarzio Model P pickup, on the other hand, makes a fantastic characterful sound, but one that isn't so flexible: it needs playing in a certain way to sing out, and if I try to vary my touch and play more expressively, the tone doesn't follow me, it just falls away.
I like having the choice.