I'd always thought sleep was for helping to retain memories, not erase them.
During sleep, we are not recording nearly as much data as when awake, giving the brain the opportunity to prioritize which earlier experiences need to be retained in long-term storage.
Many theorize that during REM sleep, while dreaming, we are actually re-living various experiences gathered throughout the day. By re-examining these experiences, they have a better chance of being retained long-term.
Remembering a pretty sunset years down the road may be pleasurable, but will not help you stay alive in the physical sense.
On the other hand, remembering to immediately jump into the tree when catching scent of a predator you haven't run across in quite some time, just might save your life.
It's this latter form of experience, getting put into long-term storage partially by initial experience, partially be repetition via dreams, that helps us to enjoy more sunsets.
The former will fade, leaving just a shell of its presence, if any.