There are a lot of factors that work against this series in how marketable it is, really.
-The odd-man-out position it has with American broadcast standards: too violent for kids, too childish for adults. DC doesn't really fit anywhere, which makes it forlorn in finding an American audience.
- The genre it's in (
Kindaichi Case Files also has this unfortunate problem; Tokyopop releases volumes very rarely and refuses to pick up the rest of the series until the poor sales improve) makes it difficult to market compared to an action series or a sugary romance series. Detective/"whodunnit" fiction isn't really big with American kids or teens unless it's crime/action/forensics-based. Europe and Asia have contributed quite a bit to the detective fiction genre with the mysteries DC is noted for, which may explain why DC has appeal in those respective continents.
And I'd say this one may be the biggest:
- The out-dated artwork and overall quality of the earlier stories and episodes. Episodes of Naruto and other popular action series are often much newer, animated in the early 2000s at least. DC's first episodes were aired more than a decade ago and are relatively low-quality in comparison to mainstream series. The artwork also has an 80s/90s look, so the design may look weird to Joe Average Anime Fan.
Tl;dr: DC doesn't have the mass appeal it would need for it to be popular with most anime fans. I was going to put length and repetition in there as well, but most Japanese action cartoons are well-noted for repetition as well as length, and they're still very popular.
Plus, VIZ did a horrible job with translation @_@
Please. Just because some of the names were changed doesn't make a translation horrible and absolutely unreadable. Once one gets past the names, the translation's spot on. I'll admit that the earlier translations by Naoko Amemiya were loose and redundantly literal (and the quality of the pages and editting was shoddy, due to their age), but she slowly improved, was replaced by Tetsushihiro Miyaki and he's done very well with the flow of the translation and its accuracy. His translation actually made the series funner to read, IMO.