I believe it was the Ramchal who said that not wearing tzitzis is one of the worst things a person could do, precisely because it is not a chiyuv.
The mitzvah as we know it today is a fashion statement, declaring one’s pride to be a member of God’s army. Being ashamed of that is, in a way, being ashamed to be a Jew.
Imagine a soldier in the IDF telling his commander that although everyone else wears green, he wants to wear blue. It’s never happened.