Hi everybody! Chris is encouraging a new era of developer/player interaction which I’m pretty excited about. So I’ll add my 2 cents to this thread. I don’t speak for all devs, but here’s what I personally would find most helpful…
Josh Foreman’s Tips for Constructive Feedback:
1. It’s most helpful if you state your request or actionable item at the top. Then your reasons below. This helps us find and reference your post, pass it around for discussion, etc.
2. Don’t assume the reason that things are the way they are due to developer incompetence, laziness, apathy, stubbornness, greed, selfishness, lust or any of the other deadly sins. There are other possibilities beside developer personal defects. “Just” changing one thing usually has ramifications on other things that are hard to anticipate. An MMO is an incredibly complex web of interdependencies, and tweaking any individual part runs the risk of breaking many other parts. That’s why we don’t typically jump to instant ‘fixes’ (even though it’s tempting!) and why things that seem like obvious problems can take a lot longer to address than many would intuitively think they should. There is no MAKE IT WORK button that we refuse to push out of spite. Even if that were the case, it just doesn’t make sense to insult the party you are requesting something from. In what part of the real world does that ever work? 
No one wants to ‘slap you in the face’ or make the game less fun. We love you guys, and are thrilled that people play our game!
3. Don’t assume that we can just rearrange resources to work on your particular issue. Most of our teams are very specialized. It takes a long time to build the experience necessary to be a good productive member of the PvP, Story, Systems, or any other team. Just because we have X programmers working on bug fixes and Y working on Gameplay improvements, doesn’t mean we can arbitrarily move those numbers around. It’s just not that simple.
4. Please stop calling us liars when we fail to implement something we intended to months ago, but for some technical, balance, or other reason found it to be untenable. We can’t be very open about our plans if every word we say is taken as a contractual obligation. Imagine if every word you said to your friends were recorded and played back at the most inopportune time in order to make you look like a fool. You’d probably clam up pretty quickly. Making an MMO, especially one as experimental as GW2 requires… experimenting. Requires making plans, following through, finding dead ends, back-tracking and trying something else. Sometimes that means that we will state a clear goal, test it internally and find out it just won’t work. The idea that this means we don’t have a clear vision is wrong. There is a difference between a core vision for our design principles, and the implementation of specific systems. We are very clear about the mountain we want to scale, but whether we do it in 4×4, on foot, with a grappling hook, or a hot air balloon are all contingent on the terrain we discover as we progress.
5. You are not “all players”. Please stop saying “Players want X” just because you want X. The fact is that players want X, Y, Z, and the rest of the alphabet, and most of those desires conflict with each other. And I guarantee you, anything that the vast majority of the players want, we (as players of our own game) also want.
If you don’t understand why something the vast majority of players and the devs want is not implemented, see the above points 2-4. I have a people-pleaser mentality, so this is one of the hardest pills for me to swallow as a developer. I want EVERYONE to be happy. Unfortunately, the rules of the real world make that impossible. 
So there you go. That’s my advice. I really believe that devs and players can work together in a healthy way. And this is my advice for making that a reality. Thanks for reading!