My ol' Why Not Mozilla? page recently wandered onto programming.reddit.com, though I wouldn't go clicking through for the comments.
Some specific criticisms are out of date, but the gist still seems true.
On the off chance any Mozilla people ever read this, the feedback has uniformly been positive about the piece. If any of you still harbor delusions of platform-ness, it's not going to happen. The developer community has been burned. I don't think we'll ever trust the Mozilla team to promise us a platform again.