Considering how the human mind works, we all have memories of great adversity and strife that we'd like to go back and do over the "right" way. Perhaps we said the "wrong" thing to that special someone, or failed at trying to impress people we admire. Maybe we just wish we studied harder for that test, or practiced more before the concert. We could have forgotten about a birthday, or possibly been inconsiderate and heartless to someone we cared very much about in a fit of emotion or rage, or maybe we just got three strikes instead of a home run, because we couldn't know what life was pitching at us at the time.
Personally, I have a list of about 30 things that I would go back and "fix" or change if I had a time machine///different save slots, and if I really stopped to think about it, it would probably end up being over 300.
That said, I think everyone has this feeling. Over time, we gain more knowledge and experience, and understand more about how the world works. It's frustrating to be placed in a situation due to your own ignorance, or a poor, uninformed decision you made, or just making the wrong choice, when they both seemed to be equal (apple instead of an orange, a left instead of a right, say...)
Unfortunately, the way our lives work, time marches on. Even indecision is a decision, as while we think, the window of opportunity may close, and it's not Ocarina of Time - you can't just hit the switch that raises the iron bars for 20 seconds for you to run to the other side of the room. And even if you can, who says you'd be able to run over there anyway, even if you knew you had to, and knew you wanted to, perhaps you start running and break a leg, and you can't ever have the chance to run it again...
I can safely say that quicksave and quickload would be the one command I would choose to take from a computer. Copy paste would be nice, but I think F9 would be it. Then again, F5 was quicksave and F6 was quick load in most of the games I played. Heh.
