Because in the show the two Beamjump instances were both Kamehameha's. Against King Piccolo (Dragonball, Goku) before punching through his chest, and against Frieza (DBZ, Goku again) beamjumping to evade one of Frieza's explosions.
I think Beamjumping should be toned down though, it's faster than swooping. Seeing as in both instances it was a boost in speed rather than a handy means of transportation, I think it should have a maximum length of 160 units before breaking off, but you maintain the momentum which diminshes, so it's sort of like a catupult to quickly get you out of an area/fling you into someone fast for melee, rather than a way of just getting about. It would be more like the show this way.