Actually, PowerPuff Girls Z was animated as a 24 episode minute series as a whole, rather than individual "11-minute segments". It's just divided as two parts, as a tribute to the original PowerPuff Girls series. If both segments had different Storyboarders and animators, I'd agree. Crayon Shin-Chan would be a perfect example of this. The episodes are just divided into two parts. It's not unheard of. Look at Keroro Gunsou.
Regardless though, the artical most certainly got the popularity of the PPG wrong in Japan. The reason the series was continued in the fashion it was, was because the series was popular enough in Japan to warrent it. To be quite honest, I would have to say the show is more popular in Japan than it is here, honestly. Japan has also had a couple "exclusive" things animated specifically for Japan. The 2006-07 Newyears PPG marathon, a segment on a comedy show that aired on Asahi TV. Maybe others, I honestly don't know.
Also, we have information that may as go back as far as 2004 that PowerPuff Girls Z was going to happen. (A domain was registered back in April 2004. SOMEONE found it here, but I cannot for the life of me remember who. Two other domains were also registered by Turner, but that was earlier this year or last year, if I recall correctly.) That, and the general PowerPuff Girls fanbase in Japan is actually quite huge.
Also... Maybe PowerPuff Girls Z was popular in Japan. The general ratings for the timeslot the show aired in really didn't indicate as such, but the ratings appeared ot be normal for the timeslot. The series hit the 3.0%+ once or twice around the final set of episodes or so. However, the DVDs, more specifically the Limited Editions in Japan, seem to be selling rather well. They keep popping up in CdJapan/Neowing's Top 5 DVDs of the Day list (not sure what catagory, but I'd assume it'd be "Animation".).
Well, there's my useless information.