Add a feature ingame (/feedback) that can allow players to provide feedback as they're presented with specific situations.
I'd like to see a free search feature added to all venders - having things listed alphabetically is fine but when there's 200 items that's still a lot of info to go through to find exactly what you're looking for. Having a true search feature would allow you to pull up what you need specifically without adding extra time searching. Now that quick travel has added costs and running around takes more time, something that shaves off a few seconds/minutes would be nice.
I'd like to see missions more consistent - there are several heroics/missions that if grouped and the person who 'owns' the instance completes the mission, they're the only ones that get credit which means doing it again for members of the group. Examples are A Rock and a Hard Place heroic on Belsavis and Anti-Toxin Recovery on CZ-198. There are others but these I can list off the top of my head. Please fix these!
Can we please get other types of mechanics besides knockback and stun-locks when dealing with boss mobs - or mobs in general? There's nothing more annoying when engaging the enemy and your opening attack is stun locked or you're immediately punted across the room...and then slowed. Occasionally, it would be ok but it's nearly every single encounter. If you want a mob to have those abilities, that's fine, just maybe not the OPENING ability.
I'm sure I have more ideas - the /feedback feature would be helpful so I can address a suggestion at the time I encounter a situation.