I didn't think defragging was that important with the new file system. Wasn't that one of the selling points?
I tried a little experiment a few months ago, by purposely not defragging my XP computer, for 2 months I let the thing slide.
After the first month, I noticed the computer starting to slow down slightly, even though I was still doing spyware and virus scans every few days, these scans were also getting slower as time went by.
Come the end of the 2 months, I opened the Windows Defrag application and clicked "Analyze", I was met with a long red bar in the disk usage space, with a few blue bars in amongst it.
I am of the opinion that Windows XP, merely throws files into the disk on you computer in any place that it will fit, no matter how long it will take to find it again later.
The reason I went looking for this Smart Defrag program in the beginning, was that I found I was having to do 2, even 3 defrags with the XP version to even get the drive to anywhere near normality.
And I also found that there is also a point of diminishing returns with the XP defrag as well, after 3 defrags, it will refuse to defrag any further.
To answer your original question,
If you didn't need to defrag your disk, why then did XP come with the Disk Defragmenter application?
I'm pretty sure it wasn't put in there for the fun of it, or was it?