Music is a foreign language and it has many dialects. There is vocabulary, grammar and syntax, meaning and context. As with any language, the better you understand all of its subtleties, the better you can express yourself in that language.
If you compare the harmonic language of Bela Bartok with Serge Rachmaninov’s you can see a significant difference in their use of dissonance even though they lived at the same time. The most stringent dissonances in Rachmaninov’s music would be almost consonant in Bartok’s music.
Understanding the syntax of music allows for a quicker and more accurate recognition of patterns and structure. Without this understanding everything is meaningless randomness which happens to sound nice. While French may be pleasing to listen to as a harmonious language, I have no idea of the meaning behind those sounds so my appreciation and understanding is severely limited.