The reason Kamelion saw so little action is really sad. The man who invented and controlled the prop for the show died unexpectedly. Unfortunately he passed away without leaving behind any documentation about how the robot worked, so the production staff neither knew what to do with him nor how to do it, and it was decided to retire the character. That's why Kamelion doesn't even get a mention or appearance in The Five Doctors, despite him having literally joined the TARDIS crew in the previous episode. :(

Kamelion's gotten a lot of attention and character buffing in the Big Finish audio productions, as well as some of the Virgin Past Doctor adventures, and even the comic books. Some of it's pretty cool, some of it's extremely weird (Kamelion and the TARDIS at one point have a child together, which Peri has to care for--WTF?!), but Big Finish and Virgin have both been great at filling out back-stories for minor characters. Turlough features in a number of them as well, and gets a nice fleshing out too of his time before the Black Guardian gets his claws into him. :)