I just know they're better for me.
I like to work on my own bike and I enjoy the tolerances, or relative lack thereof on C&V bikes which make them more friendly to curious tinkering. Modern stuff in general is not as serviceable to the shade tree enthusiast and some stuff either works, or you dispose of it and replace it when it doesn't. Compatibility is also a bit of a nightmare between standards these days, no thanks. New stuff looks like plastic... oh wait... it is.
I think C&V looks far better, hands down, and since I don't live my life by graphs and metrics alone, this means a ton.
I very much enjoy the concept of conservation. Taking a rusty, oxidized bike and cleaning it up for another 40+ years of use is something that a lay person can't do with carbon fiber. Aluminum is okay I suppose, but I don't see many aluminum bikes that spark my interest. They're also very stiff, which I enjoy for a sprint here or a hill climb there, but I wouldn't want to live with them.
The people. I find the people behind C&V to be the greatest perk. The C&V crowd is much more into appreciation and enjoyment vs. squabbling over who has the stiffest, the lightest, the most watts... ugh.
Lastly, the ladies love C&V bikes. A dapper gentleman on an old steel frame is a much more attractive mark for conversation than any man whose guide is his wallet and a gram scale.