There was no rush. We made a concious decision to speed up the development of GStreamer 1.0 by porting applications to it. A library cannot become 1.0 without that happening. With applications being ported, you find problems in the API and because there are programs using the new library, people can discover bugs in them. Meaning: it becomes more stable.
When the decision was made, the schedule of Gstreamer 1.0 was supposed to match with GNOME 3.6. Obviously there is risk involved with such a large library. Something that is actually considered.
GNOME has been doing this with loads of libraries for the last 10 years or so, but as that all went ok I guess it was not noticed
