As far as I know, there is no accepted science to dream interpretation. In fact, there's no science to it at all. Evidence has shown that indeed, dreaming draws material from people, places, and things in our lives, but there's absolutely no scientific data out there (that I'm familiar with) that links dreams to anything meaningful in our actual daily lives.
If anything, dreaming and sleep is an opportunity to "replay" patterns of neural activation that occurred during the day, leading to consolidation of long-term memories. I wouldn't take anything on that Wikipedia page seriously.
Other arguments for why we sleep and dream:
(1) We may sleep to repair our brain or maintain homeostasis within the system. This would suggest that there's a substance in our body which requires sleep that increases its need over time. This possibility is evidenced by the fact that you can die of sleep deprivation -- but evidence against is that some amount of deprivation doesn't set you back all too far. (Also, why does sleep feel restorative, if it's only maintaining homeostasis?) There's increasing amount of evidence to suggest that improved circulation of cerebrospinal fluid in the brain during sleep serves to clean the brain from toxic metabolic byproducts of daily activity.
(2) It's also possible that sleep and dreaming serves the body's overall safety. This argument stems from value long-ago in sleeping during the dangerous nighttime, when predators and other dangerous animals generally have the upper hand over man. This seems reasonably vestigial in humans, though...
(3) It also may be the case that sleep and dreaming is effective for conserving our neurak energy over the course of the day. Indeed, slow-wave sleep is associated with reduced cortical activity -- but then again, REM sleep features high activity.
(4) An even more powerful possibility is that neural reprogramming is dependent on sleep. This is evidenced by consolidation effects that occur while we rest, and the fact that less interference occurs during the sleeping hours (see Jenkins & Dallenbach, 1924, if you want to read a real classic). There are many minimal sleepers out there, though, that are high functioning, so what does that mean for this theory?