computer

Is it a homework?
(1)Double sided and double layered disc are expensive to manufacture. Moreover, due to DVD's fixed resolution at 720x480, extra storage doesn't improve the picture quality much, can only improve compression loss, or lengthen movie time. So the market don't have a big demand on it.
(2)To achive better quality video disc, there is already an alternative, blu-ray disc. Therefore, making limited improvement to a decade-old DVD standard less attractive.