I can't comment on the development process, as I'm not involved. Sometimes things don't work out as anticipated or even hoped. That's something I can accept.

The enormous failure of the WordPress 3.6 development cycle is the lack of communication about issues and ability to set reasonable expectations for the plethora of people who need to run their sites and businesses. The lack of communication is inexcusable. If there is no post-mortem, then future developers may run into the same problems without any guide to help them avoid the problems with this cycle.