I felt the characters were sufficiently developed for their various purposes within the movie. We spend as much time with them as we do LUKE/LEIA/HAN in ANH.
What exactly do we learn about Chirrut Îmwe, Baze and Bodhi Rook other than the templates for their characters? Not much…Can’t say the same for Luke, Han, Leia, Rey, Finn and Kylo Ren.