There are some reasons:
- Plugins — I use many wordpress plugins, some are custom hacked. I need to check them for updates or search for similar plugins that support version 2.3.
- Tags — As you know, WordPress 2.3 supports native tagging. Currently, I do not use any tagging plugin. All the blog tags you see on previous posts are manual HTML codes. I hope to have a script to import the manual tags to WordPress 2.3.
- Blog editor — I need to check to make sure that my favorite blog editor fully support WordPress 2.3.
- New theme — I have a new blog theme under development (since long long time ago). I wish to launch the new theme together with WordPress update.
Anyway, I should do the WordPress upgrade soon before the release of version 2.4 in December 2007 (check WP roadmap).