In the early 1980's, Hanna-Barbera experimented with the Scooby-Doo franchise by sending Fred, Velma, & Daphne on a lengthy hiatus, putting the emphasis squarely on Scooby & Shaggy (along with Scrappy-Doo). A lot of fans are not very fond of this period in Scooby's history, largely because of Scrappy's presence, but also because they got away from the traditional format in favor of slapstick comedy.
In 2006, Warner Bros., having learned very little from the previous experiment, decided to send Fred, Velma, & Daphne away again, but not too far this time. The trio would only be recurring cameo players in Shaggy & Scooby-Doo Get a Clue, which spent two seasons on the CW.
The plot this time has Shaggy (Scott Menville) inheriting a fortune from his supposedly deceased uncle, Albert Shaggleford (Casey Kasem, who seemed to have a monopoly on Shaggy's relatives). This allows Shaggy to upgrade the Mystery Machine into a high-tech morphing vehicle, kind of like the Chan Clan's Chan Van more than 30 years earlier. There's also an ongoing villain, Dr. Phineas Phibes (Jeff Bennett), who wants Shaggleford's nano-tech technology for his own nefarious schemes. Phantomdarknes uploaded the open:
The flash animation doesn't fit Scooby and Shaggy at all. Also, Shaggy has discarded his signature green shirt, which to hardcore Scoobaholics may have been a major turnoff.
This marked the first series in which Casey Kasem wasn't voicing Shaggy, although he continued to essay the part in the direct-to-video movie series until last year, when he passed the mic over to Matthew Lillard. Menville's characterization as Shaggy, like previous would-be heirs to the role (Billy West & Scott Innes), wasn't solid. Like, he tried, but the faithful weren't buying.