I think Adric is a lot better than he seems to be given credit for in some circles.
He did seem a bit whiny when Peter Davison took over from Tom and I can see how that would have rubbed people the wrong way but I enjoyed his stories with Tom a lot more and thought it was intresting in "State of Decay" as he almost seemed ready to leave the Doctor & Romana to their fate if it meant saving his own neck which to me showed he was quite resourceful.
Whatever anyone says about Adric his departure in "Earthshock" is the most memorable exit a companion has ever had and is ever likely to get...he caught a planet in the face and wiped out the dinosaurs...talk about going out with a bang!
Killing someone off like that wouldn't happen in today's show as the production team would be too afraid of getting complaints from parents of upset children but at the time I expect it brought back a feeling of "anything can happen" that allowed viewers to suspend their disbelief and believe the good guys wouldn't always win.
"I'm not a human being........I'm a Time Lord. I walk in eternity"