Well, i like the ADR concept, but to define what's best for a Joomla Framework, there should be a definition of its goals.
The Joomla! Framework™ is a new PHP framework (a collection of software libraries/packages) for writing web and command line applications
First i would disagree that a framework is just a bunch of packages. But if Joomla does see it this way, there is no reason why MVC, ADR or XYZ Packages can't be part of the framework at the same time.
IMO a framework is on top of that. It's not just a collection of packages, it's an engine for developers to build (more or less) awesome applications.
But back to topic: It would be great if we could offer multiple architectural patterns for the same application. So an application can change it's pattern in relation to it's context.