I honestly dont think there is really a demand for dbz its has been done to death.
Um no.. We have DBZ on Hub TV and Nick here in Florida. DBZ is far from dead. Hot Topic still gets shirts in, and they sell!
You're both right... in a way.
Super Sentai ( Power rangers) Is massively more popular globaly, than Dragon ball.
In japan, Dragon ball is not the merchandising giant it once was... though Super sentai is still going crazy strong.
so Super Sentai gets more attention.
So then why are we still getting Dragon Ball figurarts?
Funny answer to that. It's important to note that in Japan, the Dragon Ball figures are ONLY sold as a Tamashi Website exclusive. this market is EXTREMELY small and niche. it's one of the reasons why the line was canceled for a while. But, suddenly, there was a demand for these figures... from outside japan.
You see, the /toy/ board on 4chan suddenly noticed these figures, and started picking up Goku and Piccolo shortly before the line was canceled. This lead to lots of silly pictures of things like piccolo going to Tea parties ( I'm NOT making this up) getting angry at something trivial, and then blowing **** up. ( WHAT?! NO SUGAR?! MMMMMAAAAAAAAKENSO!) much like "hentai woody" this kinda went viral. people loved the detail on piccolo, and the articulation, and more and more people started to take notice.
This spirals like crazy. More ad more people discover them. they start showing up on toy review shows and sites, etc. Love of the "over 9000" meme helps tremendously as well.
Suddenly, there is an American Market demand for these things. Blufin ( the american distributor for Bandai and Tamashi nations) brings A repainted Goku to SDCC... and he SELLS OUT.... and people want more. Bluefin Buys up ALL THE REMAINING STOCK of Piccolo they can get in japan ( he was shelfwarming like mad, and on clearence everywhere) and imports him to the states.
HE SELLS OUT
Bandai Takes notice of this market at some point, and restarts the lin, JUST as american Market Exclusives, and Tamashii web exclusives.
Very VERY literaly, the American market sales of these figures is the ONLY thing keeping this line alive.