If you are using Websockets or AJAX the connection limit can become an issue.
Also some users always write www in front of the domain. Although some browsers will just redirect to Google. So if you check browser referer a lot will be from www.google.com?q=www.yourdomain.com
Also my www recommendation is for commercial websites who tend to have multiple subdomains, more traffic with HA requirements, and a more complex setup than a static website.
"I'm curious why you say you're 'very much' in the WWW camp but you don't use it on your own site." would not have the same tendency to register as an attack.
When you see something that you might think is hostile, it's often more productive to give them the benefit of the doubt and presume that they intended good faith but have different conversational norms from you. In the best case, they meant well, and everything proceeds nicely. In the slightly worse case, they didn't mean well, but you've helped de-escalate, and things are back on track for a nice discussion. In the worst case, they get more blatant in their attacks, and at least you'll find out that productive discussion wasn't possible anyway. Not much downside, and lots of upside, in my experience.
> End users save an extra DNS lookup
Most intermediate resolvers will return both the CNAME and A record in one response anyways.
Another issue with naked domains is that all the cookies are automatically served on subdomains as well. It's just another hassle to worry about when trying to keep the cdn clean or wondering why a session works only in specific cases.