Leaving the cynicism and hyperbole aside, what bothers me are not the e-mails, but the double-sided stance of Firefox as a project, in feature-parity bugs we get the draconian speech of "oh no, we must follow the standards strictly, it doesn't matter if every other browser work fine and it doesn't matter if you already spent your time to develop a patch", but in the outside world we get the announcement of support for webkit-prefixed properties (to name an example).
As a developer, this destroys the credibility of Firefox when it comes to interoperability, and in the outside world I have been perceiving a rise of Chrome-only web applications, this can't be a coincidence.
There's a lot of people at Mozilla, and they talk fairly freely, so the result is an inconsistent message. Not everything you see is a stance, much of it is people trying to figure things out and communicate the decisions-of-the-moment.
As far as web compatibility and standards, the inconsistency is part of Mozilla. Is Firefox a tool for open web standards advocacy? Some in Mozilla feel that way. Do we just want Firefox to render things well? There's a whole team for that too (https://wiki.mozilla.org/Compatibility). And of course there's Bugzilla, which can feel like a lottery – it's very hard to know who you encounter when you enter the project through there.
This stuff is hard, and making the right choices is hard – I'm sure Mozilla has not always made the right decisions, but I personally prefer ongoing struggles to make the right decision over a consistent and credible stance.
Firefox's policies are no different from those of Chrome in this regard.
There is in fact a middle ground between "free for all, implement whatever you want" and "implement only what is precisely required by a standards document". In fact, this middle ground is the only way to make a practical browser engine. The two extremes are untenable.
As a developer, this destroys the credibility of Firefox when it comes to interoperability, and in the outside world I have been perceiving a rise of Chrome-only web applications, this can't be a coincidence.