lightning wrapped around the beam... like the lightning that flickers when someone goes SSJ in the series? The lightning that radiates from their body, flickering on and off, making them look like walking powerhouses? They would have to make a sprite for that, and have it turn on and off and have it remain attached to the player or the beam.
In short it is just a little tidbit, that though it would look friggin sweet, would needlessly lag people and would be more crap for the coders to code, and more spites for the... spriters to sprite
, and they are already swamped (I'm guessing) with working on fixing things in the Beta as is.
maybe in an official release, but I doubt in a beta.
There already is lightning during transformation, watch Goku.