In E. K. Johnston's new Star Wars novel, Queen's Hope, we learn a surprising (you could even say shocking) detail about Emperor Palpatine and the Force Lightning he unleashes. Turning to the Dark Side and becoming a Sith opens the door to powers the Jedi can only dream of, though it also takes its disciples down a path that leads to what might be best described as pure evil.
While we've seen Palpatine wield a lightsaber, it's become apparent that he most enjoys using Force Lightning. The Rise of Skywalker even saw him let loose with a Force Storm that brought the Resistance's fleet to its knees. So, it's clearly a powerful tool, but there may be another reason why the Emperor so enjoys wielding this specific Dark Side power when battling his many foes.
In Queen's Hope, we see a number of key moments from Palpatine's perspective, including one that takes place shortly after The Clone Wars begins. Furious, he returns to his sanctum and uses Force Lightning on a Sith relic meant to absorb that energy. The suggestion is unleashing this power is akin to an emotional release, and one Palpatine has no doubt become somewhat addicted to.
The fact Palpatine's rage has built to a point where he can only control his temper by using Force Lightning this way adds a new dimension to these powers. It also explains why an evil such as this one would turn to that rather than his lightsaber as it allows the Emperor to quite literally let his anger flow through him...and lay waste to those who dare try and stop him (like Mace Windu and Luke Skywalker).
It's also interesting to think about what this means for the Sith that don't use Force Lightning. Count Dooku did, of course, but Darth Vader and Darth Maul were never shown utilising that ability.