It's not a terrible name, it's just that we've forgotten the real meaning of "complex" and use it as a synonym for "complicated".
"Complex" was originally justifiable but it should be renamed to reflect changes in the English language.
Wouldn't that cause much, much greater confusion due to mathematical nomenclature being a moving target rather than remaining stable?
There may be some amount of drift over time, but you can go to the research library of any university math department and find books from pre-WWII that are still totally readable because although style has shifted somewhat, the basic nomenclature hasn't.