I'll turn the question around and ask why you would wear a shirt of a particular color, unless that color had a specific meaning to you. Although many on the forum choose a tartan kilt because of some affiliation, others wear a kilt simply as a garment. The kilts I wear most are in tartans that have some connection for me, but I do have others. Understanding why different people make different decisions would take forever, as each person has a different reason.