This was an intentional choice fromPR 1613. Unfortunately this has caused some downstream headaches for us (speaking on behalf of the yt project).

The issue is that we distribute yt using a bash installer script that builds all of yt's dependencies from source. Now that we've updated to use matplotlib 1.3.0, all pylab imports fail on OS X with a RuntimeError.

The relevant yt issue is here:https://bitbucket.org/yt_analysis/yt/issue/642/cannot-import-pylab-on-os-x-using

Wouldn't it be possible to fallback to another frontend rather than outright failing? Our suggested workaround is to use tkagg instead of macosx but that's a bit nasty since it doesn't fix the fact that pylab is broken out of the box for our OS X users.

For what it's worth, we've never heard of issues with the macosx backend. I guess it wasn't fully working on our non-framework install of python, but the failures were so subtle that no one ever noticed.