The majority of all supporting characters outside of movies are really bland. “Barkeep”, “Guard”, and “Thief” are fully comprehensive summaries of their entire personalities. Even worse when it happens to main characters. And it’s not that movie are immune to it. There are movies with characters written like that. Generally bad movies.
But think for example of any other characters from Conan stories. If you are a commited fan, you might be able to give a name to “the princess in People of theBlack Circle” or “the sorcerer from The Tower of the Elephant“. But it would be close to impossible to describe them as characters instead of the specific things they did. The Lord of the Rings is even much worse. Describe anything about the characters of Legolas and Gimli in the book. One is an elf and son of Thranduil, the other a dwarf and son of Gloin. That’s about all their is to them. I think this is not just wasteful writing, but also lazy.
My solution to this is to draw up a character sheet for all characters that are added to a story. Not defining them by various numbers or parameters, but making a list of traits that could distinguish them from others and make them memorable in some way. Unusual physical features, iconic pieces of clothing, quirky habbits, notable forms of speech, a special weapon or tool. Anything that could make the audience remember the character as “that guy with the thing” instead of “the guy who did that”.