Probably the same reason we don't have them on our homes. Cost vs. benefit. Not to mention the fact that they are somewhat fragile and would be a maintenance nightmare. Durability is more of an issue than is flexibility I believe. Case in point...



Planes have alternators where are quite efficient generators of electricity.

I don't want to sidetrack your thread but I'm curious why we don't harvest the static charge rather than using wicks to dissipate it. Maybe some aircraft do and I'm just not aware.