> A few clicks and XP SP3 looks exactly like 2k, with a few useful features thrown in.
There wasn't much added to Windows XP over 2000 in the original release of XP (service pack 3 was released 6 years (!!!) after XP was originally launched. So it's not really fair comparing XP SP3 to Win 2k). I remember this era in computing vividly and it took a few service packs before XP really came into it's own. However you still paid the price running XP because it demanded double the hardware requirements to run when compared with Windows 2000. So sure, you could disable themes in XP but for many people sticking with Windows 2000 was more appealing because you had more preferable defaults out of the box plus less bloat / hardware overhead too.
A decent number of not-ancient floss software supports it as well. Not so with 2k. Add thousands of security patches and firewall, and the choice is clear.