So my question to you is: Why is being unique so great?
Being unique means that you're irreplaceable, and that in itself is a very powerful motivating factor. If you can reduce an individual down to a set of criteria, each one of which the individual can be considered to have a more or less desirable skill in, that person has now become replaceable. Now all it takes is someone better at, say, riding a bike to come along, and instantly that person has become less-than-desired, and nobody really cares because the new person can easily fill that person's spot.
Being unique also means that no matter who you are, or who you're interacting with, that other person can always learn something about you. There is no way to quantify you, as long as you're unique, because nobody can look at things exactly like you would, or predict exactly what you're thinking. Why is this so great? Because it means that nobody can ever take your place. It means that as long as your own set of perspectives and opinions still has relevance to a group, you are useful and interesting to a group. Somebody can't just step in and kick out three people by dint of being able to see things and speak and react exactly as they would.
There's also the pioneer factor as well. If everybody is unique, then it means that nobody's ever lived their life before. It's instantly a sort of adventure, because nobody knows how you're going to turn out in the end.
To some extent, people do give up uniqueness so that they can be a part of a group and get along better with people. (Imagine being a part of a community where everybody was "unique" that they all spoke their own language...or all had their own completely different interests. Finding common ground to bond on would be difficult, to say the least)
Let's carry this over into artifacts as well. Would common sense dictate that one completely unique piece of art by a famous artist would be more valuable, or one of a thousand pieces of art mass-produced by that artist? If you had to choose one or the other, which would you destroy? Again, being unique is valuable because once that one piece of art is destroyed, the idea it contained is lost forever. If there are a thousand other copies that are virtually identical, well, it's a shame that the original was destroyed, but the idea still remains.
So in some sense, being unique can be a weakness, because it means that a person also risks losing what they stood for (if they stood for anything) or anything else that they value about themselves, forever, because they are unique. If you have a talent for art and you choose not to exercise it, and you die, that talent and whatever it may have produced is gone forever. Nobody else can step in and make a prediction based on your psychological profile or whatever. If anybody wanted you to produce art, then they will be sorely disappointed. And if your art would have gone on to change society, or have an impact, or even just become well-known, you will have completely lost that opportunity to make a difference.
Of course in that case you probably wouldn't feel too guilty about it, because you were dead and would have either no concerns, or other, more pressing, concerns in the afterlife of your choosing. But suppose you have a great idea for a painting, and then you suffer some sort of paralysis. Well, there's not really any way for you to actually make that painting. Sure, you can explain it to somebody, but they won't have your hands and they won't have your brain. The painting produced will not be what you would have produced, and it may very well never be completely satisfying.
And of course it doesn't have to be art, either. It could be some form of writing, a business (or product), something fun you want to do, or anything else that you can personally contribute to.
And finally, but by no means the last reason, if something is unique, it cannot be compared to anything else. If you are truly unique, nobody can sit down and judge your absolute worth. That is a very powerful motivator to be "unique", because it means that nobody can judge you or argue that you should or shouldn't do something to simply be "better".
And technically, not only is each person unique, but on an atomic or subatomic level, they're instantaneously unique. That is, the person you are
this instant will never exist again. The atoms and energy patterns that make up your body will never be in the same configuration again.
