I don’t know anything about AD, so this might be a stupid question: can you not just run a web server on the same host as the AD server or port forward all HTTP traffic to a different server?
A domain controller on the internal network might not be the right place to run a copy of the public-facing content HTTP server (which might be in a datacentre, or even managed and run by an outside party, and might not be served by IIS). Then there are considerations of firewalling rules, browser rules, anti-virus rules, and even DNS rules for machines on the internal network that access a public WWW site that DNS lookups map into non-public IP addresses. (To prevent certain forms of external attacks, system administrators have taken in recent years to preventing this very scenario from working by filtering DNS results.)
Having a disjoint DNS namespace (and the needless make-work that it creates) is the issue, more than running HTTP servers on all your DCs to do redirects. There is absolutely no practical advantage to running an Active Directory domain with a public DNS name. It's all downside. It has always been all downside, and anybody who had any experience with DNS could see that all the way back in the beta and RC releases of the product in 1999 and 2000.
