The fact was that 650mb was the 'standard' for cd-r's was amazingly stupid. They did that basicly to compensate for absolute crap media, since the very bad stuff would work very poorly at the edges. Since then they've really improved media (even the unbranded cheap stuff), but as far as I know they didn't compensate for bad media as much when they created DVD. The main reason was because any dual-layer disc would be required to have very good read characteristics at the very edge of the disc when it switched to the second layer. Also, fitting more before data that crossover point (despite it being single-layered media) isn't as easy to due as it was with cd-r's.
On a normal [sized] blank they fit over 33% more onto cd-r's (74min vs 99min), but I think that big of a jump isn't possible with dvd+/-r media.
v7 & Messiah2
location: Iraq; coordinates: classified; mission: replacement for 'shelled' ps2
v10 & Matrix Infinity
location: my room; mission: Army reserve...