Imagine if Cloudflare went to IPV6 only. Yes, Cloudflare's customers should know what that means, but the end users that are using the service may not be and if the error in anyway says Cloudflare, then it gives Cloudflare a bad reputation.
While AWS is a bit (just a bit) more removed from the end user than Cloudflare, there is still the potential for it not being good PR.