There is no "answer" to this question, there's no "explanation" why some people like rat rods... just as there's no "explanation" as to why other guys like street rods... or customs... or lead sleds or lowriders or donks or those wacky Japanese bozozukos or whatever the heck they're called or whatever. You like what you like, no explanation is needed.
It's like saying, "Ok, I like chocolate ice cream, can anyone explain how someone could possibly like vanilla ice cream?"