Cirrus (using that as an example) have sold around 5000 air frames in the last decade, so as long as the disposable income, or finance is affordable the vast majority I think prefer a newer more modern plane in much the same way most people if they could afford it would prefer a new BMW for £50K compared to a gas guzzling 20 year old car with less safety features and probably less reliable for £2K.
I do not think the argument stacks up for those that have the choice.
For those on a much lower budget a twin would be a scary proposition as well.
Hence the fact they are worth next to nothing.