"Us in charge! Us in charge!"
Funny, but no matter where you go, every profession thinks they should be running the show. I've seen it from product developers, designers, marketeers, accountants as well as PMs and developers.
Thing is, many *good* (and yes, there are many *not* good ones) PMs and architects have been in the development trenches, so don't come the "we developers always know best" malarkey. Does experience not count these days (ah yes, that's right, it never does to the young). When you're in a trench, you tend to have a restricted view... come back and argue when you've done something *else*. (Applies also to marketeers, accountants etc).
The other pattern I see again and again is that revolutions defined on what they're *against* are rarely as successful as those defined on what they're *for*. Very, very few agilistas are able to articulate the problem they're trying to solve, beyond "Waterfall: BOOOOO!" and if they are, are rarely able to articulate how they're planning to solve it. Principles are great, and "be supportive of your team" behavioural ones don't really require the evangelism and "Two Legs: Bad. Four Legs: Good" rhetoric.