There has been considerable mystery surrounding why Chandler Riggs’ character, Carl Grimes, was killed off of The Walking Dead midway through season eight last year. Ten seasons in, and we’re starting to see that some of the show’s actors want to leave and do other things (Andrew Lincoln, Lauren Cohan, Danai Gurira), but Carl Grimes is a major comic-book character and Chandler Riggs wanted very badly to stay. In fact, he was shocked and saddened by his own exit, and his father has spent the better part of a year ripping AMC over the decision to essentially fire Riggs.
There have been some suggestion that the network knew about Andrew Lincoln’s departure from the series, and killing off Carl may have made sense in light of his father’s exit. That hasn’t really borne out, however. There’s no reason an orphaned Carl couldn’t have continued in the same role that’s basically being filled by Henry now. The time jump might have presented a small problem for Chandler Riggs — he’d have had to age up 7 years — but Riggs was a 19 year old playing basically a 14 year old on the show, so playing older would not have presented much of a challenge for viewers who have been willing to suspend disbelief surrounding the age of characters. Katelyn Nacon, who plays Enid, is the same age as Riggs and aged 7 years in the time jump and looks virtually the same. There’s been no complaints from fans.
Another theory that seems the most plausible is that Riggs simply wasn’t a strong enough actor to carry the role as it expanded in future seasons. In fact, Riggs conceded as much in a comment on a recent Reddit post. “Been rewatching twd over the last couple of months and i agree lol,” Riggs wrote, agreeing with a fan who suggested he wasn’t strong enough in the role. “i think i was decent for the first few years, but i definitely got lazy when i should’ve utilized the writers giving me more material … i sucked when it mattered.”