If a force user gets angry enough and if they have the midi-chlorian count for it, then they can generate force lighting at that moment, as Jacen and Jaina solo both did at various times when fighting the Vong. That is why Ventress so wanted to be Dooku's student, to learn those techniques which she did not know. Only the most powerful are at that level. Not every dark side user is at a level to be able to use force lightning. When Jacen Solo flew into a rage underneath the ruins of the Jedi Temple on Yuuzhan'tar and attacked his Yuuzhan Vong pursuers with Force lightning, he later found that the blasts had burned charred holes in his palm. When Anakin Skywalker redeemed himself and killed the Emperor, his life support circuitry was critically damaged, leaving him a heavy and lifeless quadriplegic.Д«esides draining the user's energy, Force lightning had the added drawback of occasionally charring the hand of the person who used it. The deformities Palpatine displayed after unleashing a barrage of Force lightning on Mace Windu, only to have it reflected back upon him by the Jedi Master's lightsaber is an example of this.

It was thought that very intense use of Force lightning could drain the user physically, and possibly result in severe facial and body deformations. It is most likely that they just found it not worth it, or ineffective for their purposes. There are tons of reasons why one would avoid force lightning (notably they don't like looking like a shriveled hag) Just because the force wielder is dark side, does not mean they would be willing to sacrifice some of them self unless it is worth while. Force Lightning has a severe cost, it drains the very soul of the person performing it, not to mention possible physical damage on the user.

Can jedi use force lightning