I know this will be a bit frustrating for folks, for which I apologize. But on the upside: (1) you'll still be able to keep running 13.01 on Precise and Quantal, (2) the next few releases will likely be very boring from a user's perspective anyway, and (3) you'll be able to upgrade directly from 13.01 without loosing your current Dmedia library or Novacut edits.
We're dropping support for Precise and Quantal because, at long last, Dmedia is going to be officially "production ready". Over the next few months, we'll be turning on the remaining automation behaviors, including those scary but deeply important "copy reducing" behaviors.
The biggest reason we're only supporting Raring is we need a smaller target when validating Dmedia. By our current PPA stats, we have very few Raring users, and that's a good thing while we turn on the remaining Dmedia features, just in case we make a goof.
By only supporting a single Ubuntu release initially, we can do deeper validation of Dmedia. Validating Dmedia is going to take multiple physical computers running an extended simulation (at least one week per run). Right now, I don't have the time to personally do this properly for more than one Ubuntu release. I'd rather have higher confidence in supporting a single Ubuntu version than less confidence in it working on 3 versions.
By focusing on Raring, we can have a higher-quality Dmedia release ready when Ubuntu 13.04 starts shipping on hardware, just in case Dmedia starts shipping on hardware around that time (wink, wink).
And although it would be nice to keep supporting Novacut and Dmedia on Ubuntu 12.04 LTS, I think it's far more important to be forward looking and focus on making Novacut and Dmedia amazing on Ubuntu 14.04 LTS.
If you have questions or concerns about any of this, please ask!