When it comes the performance of DVD reading and writing drives, the figures and conventions are much more complicated.
The key thing to keep in mind is that a single-speed DVD-Rom drive is much faster than a single-speed CD-Rom drive - 1,385Kb/sec, compared with 150Kb/sec. Most new DVD drives are 16-speed models, 16 times faster than a single speed drive, or 22,160Kb/sec.
Unfortunately, unlike the CD-RW drive market - and thanks to a number of competing recordable DVD standards - there isn't, as yet, a single convention for the order in which the speed multiples are listed. In other words, you can't deduce at a glance a drive's read, write and rewrite potential.
Adding to the confusion is the fact that most recordable DVD drives can write to CD-RW and some newer models can even deal with more than one recordable DVD standard.
It's not uncommon for fancier drives to list half-a-dozen or more speed statistics, relating to read/write/rewrite ability on the various recordable DVD formats, and again for CD media.
So in answer to your question they are already faster then CD drives at writing so why wait?