I can understand this move. If you have a look in the WP forums for the Redux plugin, there is a quite an irrate post from a user who thinks Redux is crap coz it doesn't do anything... This user reasonably expected that a plugin on the WP plugin directory would actually, out of the box, be of benefit to their site.

Redux is a dependency of my own plugin, for which I use TGM to advise users. TGM works fine with any source location, not just the WP directory, so I'm not sure why banning them from the directory is a problem.

I do think it is madness to bundle the larger frameworks, like Redux, in your own plugin (or theme). That just makes lots of fat plugins and themes, risks version conflicts if a developer doesn't set isolate it properly (which happens a lot)

Not bundling also is better for security, as the framework will always be at the latest version (if the user does updates), whereas bundled, it could get out of date if the developer stops development of the plugin.

I really like Mike Schinkel's idea of a separate repository for frameworks. I think there is much value to the whole community in WP visibly supporting frameworks.

I am concerned that those already in are allowed to stay, as it makes it inherently harder for new ones, no matter how good they are. Mike's idea would solve that problem too.