I've had in my head a while the notion that there's an inherent power inequality at work in your average development shop. That the people who hold the roles that represent the business, project/product managers, tend to be more extroverted, that their work involves primarily interacting with people, and thus a certain personality type is drawn to that work. And the developers/programmers, have work that primarily involves interacting with machines and problems, and thus a certain and different personality type is drawn to that sort of work.
But these two roles need to work together, and they work together best when they can effectively negotiate in both directions. But the business roles tend to have two things on their side that by default tilt the healthy balance towards them: that they are more comfortable with people [but it's not with people, so much, it's with CONFLICT, right?] and they usually have the power (or are more closely tied to the people who have the power) to fire the developers.
The common failing of this relationship is the person in the business role asks for things to be built, and the person in the best position to question, doubt, negotiate over these things, the developer, is the person most likely to stray from the confrontation of standing up to the request. Additionally fueled by a genuine desire to _solve_ problems with technology - this can quickly get out of hand - which is how many products get developed.
The answer to most timeline questions should really be, ‘I have no idea.’ But the business people don't want that, don't believe they know how to manage in such uncertainty (when in fact they probably do with areas like uncertainty of income and othe financial aspects), the developers don't want that either, and don't want to disappoint, etc. - so ...
BUT - i've tried to explain this along the lines of extrovert/introvert and had two push backs. One was Greg Vaughn who basically said, if introversion is my bent, I shouldn't be punished for ‘the way i am’. And Brian Marick, who correctly points out, that it's not traits that has as much influence on our behavior, it's the situations/context we find ourselves in. (true for me, being mr. extrovert in PragProg
meetings, but reserved in the Relevance process). true in some many other times - when others find themselves doing the wrong thing due to peer pressure (the skiing accident snow crash? - all of those) -