Great idea... I'd never buy one though. You just know that as soon as it's released, Flickr will be full to brimming with tens of thousands of shots just like yours within a week I wish them well though.
Given the size of the thing ( long and skinny ), and the control box ( not all that big either ), 8 AAs makes sense ( more capacity than AAAs or 9v batteries, not as bulky as a dedicated lithium pack that would require a specific charger or charging circuit ).
I wouldn't exactly call it pointless- light painting is an art form; you could call normal painting or sculpting pointless because you can take pictures or create 3D models of objects- safe to safe that's not terribly true or a fair point...
