There is finally a blue post about the CRZ & phasing issues.
The poster, Zorbrix, says that the changes are intended to improve performance in both the client and server side of the software. I can certainly see that dividing up the players into distinct phases means there has to be less communication from server to each game client.
For example, if there are 40 people at the cathedral and one of them types /sneeze, that emote has to be broadcasted to 39 other clients. By randomly divvying up clients into distinct phases, that one /sneeze may only need to be communicated with a smattering of other people.
The post doesn't mention specifically if they're working on the CRZ issue or the phasing issue or both. But the remark about efficiency certainly speaks to phasing. (We know that CRZ comes and goes depending on the population of a certain zone, but previously Stormwind and Orgrimmar were exempt from that. I'd imagine there's just a boolean toggle for enabling CRZ per zone and why it was turned on for the capital cities is beyond me.)
Regardless, it does show one thing: there are no RP'ers on the Warcraft development team.