Spielban's finale didn't throw away any character growth. It didn't make the entire series a pointless waste of time. The three heroes altered time and restored their planet by eliminating Waaraa/Pandora in the past, but they retained their memory of the series' events, they still experienced the series' events, even when they were returned to their own timeline on Clin. Like, I imagine Helen would still be aware of her actions as Hellvira and still want to atone, for example. In Ryuki, we watched Shinji mature and Ren grow a heart, but the series ends at square one -- Shinji's an immature moron and Ren's a heartless thug again, and that as far as we know, they'll never have an opportunity to evolve.
The time element was also just so out of place in Ryuki, and Kobayashi is never able to pull it off successfully. Spielban had hints throughout the show, and even in the last verse of its theme song!