Curate, connect, and discover
Another ability ramble but Kaminari never seems to use electricity from his left hand, he uses both hands to generate massive charges semi frequently and his right when running with his Pointer, but at no point does he exclusively use his left.
Now this is likely down to him being right handed and him knowing Flemings Right Hand Law, but I was thinking in true over analyzing fashion There has to be another reason!
Then I remembered back to when I watched Avatar, when teaching Zuko lightning redirection Iroh tells him to direct all of the energy through the stomach, now lighting redirection is the movement of energy from one hand to the other, moving through the stomach as to not have the energy travel across the heart and fatally injure the user of the technique.
Now technically it doesn't seem that Denki has issues with the electricity hurting his body other than his brain but knowing him he might have taken this advice to, well I was going to say heart but that's were it shouldn't be going, so stomach then. It also might have been slight fear that the generation could damage his heart in a similar way to his brain so he uses the right hand to keep as much power away from his heart as possible.
Considering that Todoroki was based off Zuko, it doesn't sound to far fetched to me that Horikoshi included this as possibly homage to Avatar.