Cosmic King:
Just imagine the consequences of lum never coming back,many stories would never happen or events woould go altered as 4 example movie 1
Kroptik:
I'm not sure about movie 1, but in movie 3 when Lum is gone Ten, Benten, Oyuki and Ran leave Earth and even Shinobu loses her super strenght.
FallinG_StaR:
And it wouldn't be called UY anymore...
DarkDevil:
Humans would stop to be alike aliens... That is what UY basicly is about. "Those Obnoxious Aliens" is the supose translation of the title. The resemblence between Aliens and humans.