I knew immediately after TFA that the majority of this new canon ("Disney-era canon") wouldn't be my cup of tea, but there are certain things that just bother me. The treatment of supporting characters, new and old, has been one of those things. There was potential for meaningful character development for Chewbacca and Phasma, and both have been downgraded (in Phasma's case, flatly hurled down and away from the plot). Han's death in TFA was an opportunity for Disney to cherrypick the Wookie life-debt concept from the Legends-era canon and give Chewbacca something meaningful to do with his screentime. (ie. go after Kylo to avenge Solo and fulfill the debt) As of now Chewie has been relegated to comic relief, which is sad.

Phasma is even worse. Talented actress, unique costume, potential for mystery and intrigue similar to Fett, and...nothing. She gets a few Nurse Ratched-type lines, a brief fight with one of the secondary protagonists, and then she gets offed via disappearing into explosion. Why create a unique character that stands out if you're just going to off them in a conventional way