Have you noticed that sometimes as you wonder why people are complaining about being tired of unhealthy, only a few colonists are walking like 100 tiles and effecting the entire system? There should be something where we can open up a menu and see the colonists that are complaining from the worst statistics to the most convenient. And for speed purposes, they should be organized according to the problems. Anne you should be able to click on them, see where they live and where they work, and change their job without them trying to stay where they are (at least, if the job doesn't have restriction on iq)
Use to be able to, but because of the possibility of such large colonies, most of the colonists above the 3k mark are 'virtual' so those functions were removed as they no longer worked correctly.