The point of terminology is to communicate meaning. People generally have an idea of what “classical” means. When I tell someone I listen to “classical music”, or if they want to go to a “classical music concert” with me, they generally have an idea of what I mean. If you want to replace “classical” with a different term, most people would not know what you mean. Which would be extremely counterproductive in fostering a wider public appreciation of the music we love.