I understand why it is the way it is and hopefully the commitment phase will speed up as the process gets more streamlined but currently it feels like commitment is essentially a 'coma' phase - momentum builds nicely as the proposal passes through define and then comes to a complete stop in commitment as it waits for enough people to just click the one button.
This was highlighted by someone I referred to the site for a proposal which had entered the commit phase by the time he got there. He was a bit surprised that all he could do was hit 'commit' and wait an indeterminate time* before he could actually do anything. He had some questions and feedback to add but the discussion is now frozen. As someone who is never heard of the Stack family of sites before this wasn't a great first impression.
Even if the questions are frozen, I think it might be good to have some form of discussion available in the commit phase as it would keep the momentum up prior to launch and hopefully get more going from already actively engaged users during beta.
Still, this is all unexplored territory and this may stop being an issue as the Area51 system beds in to regular operations.
*. I didn't explain about the current 90% thing - I appreciate it's only temporary but didn't think it would have gone down too well on top of the inactive wait period.