This is becoming a FAQ on #perl6, so I'll list the reason here briefly.
The short answer is: This makes me more motivated to write.
Part of it feels like the (very early) decision to move #perl6 from irc.perl.org to irc.freenode.net, to encourage more diverse discussion from people focused on non-perl languages, as well as on areas other than programming language technologies.
Part of it is that I need a backstage journal to write about myself and off-topic metajournaling (such as this entry), and creating two use.perl journals for this would be very confusing.
Part of it is I'd like to put in more multimedia contents -- visiolization pictues, movies, tutorials, podcasts -- and TypePad offers much better support for these things.
Part of it is per-entry categoriestags really helps me ditching the "group everything in Day ###" format, and give separate subprojects the attention they deserve. Archiving and searching is also much easier this way.
Part of it is I have a soft spot for Atom-based publishing, having participated a little bit during its move to IETF standardization. I look forward to synchronize journals in a SVK-like manner in the future, instead of relying on <textarea> and screen scraping.
Part of it is I really like bright white background and paragraph width that is narrower than the full screen, with drops of purpleish and bluish colors. It's kinda silly, but I'm a silly girl like that.
Oh and finally, I'm very grateful to Six Apart for their generous offer of hosting this journal. Thanks folks!