>>149497366The original benefits from the fact that classical music was still sort of a living art form at the time. Still mostly music by dead guys, but Stokowski and Toscanini were actual celebrities, there were still some world-famous living composers like Stravinsky, Rachmaninoff, Prokofiev, Sibelius. Most people sort of knew classical music in a way that they don't today and the animators "felt" the music having grown up with it.
By the time Fantasia 2 came out they had to have celebrities explain why we should care, which probably suggests why they shouldn't have made it.