The absence of a meaning of life is what sets us free
The meaning of life is something which has bothered humanity for as long as we've been around to be bothered. Generations of philosophers, theologians, artists and poets have debated, with little progress either way, what the point of it all is; with answers ranging from it all being part of a divine plan, to a quest for enlightenment or a journey of self discovery.
However, as we come to understand more about the physical world, our relatively minor role in it, and our origins, it is becoming apparent that there probably is none. As the product of a few billion years of disinterested evolution, clinging to an unremarkable ball of damp rock revolving though a cold and uncaring universe, the conclusion that there is no actual meaning or significance to our existence is scientifically the most likely explanation.
This is dealt with in various ways - from outright nihilism to the focus on experience and absurdity of existentialism, to the more optimistic outlook of humanism; and in a lot of the more progressive outlooks with which I am most familiar, this is not much of a problem. However, far from being something we have to come to terms with - some affront to our existence which we must learn to bear - I see this as the best situation in which we could find ourselves.
Consider for a moment that at some point, from some divine revalation, deep philosophical insight or profound scientific discovery, we had found the actual meaning of life, and understood our true reason for existing. I really, really don't like the thought of this. Why?
Because it would mean we have a purpose.
Think of what that would entail: we would know what it is we are supposed to do. Yes, we may rid ourselves of all that existential angst, the endless pondering over the point of it all, but at what cost? It doesn't matter what this meaning actually is, to know that there is one would be a terribe, crushing blow to our sense of identity, as well as a threat to the delicately balanced social structure we have built. We'd know exactly what we were here for, what it is that some undefined being/process had intended for us, and that if we did not fulfil said task, we were failing in our mission as human beings. Irrespecitive of what we, as intelligent creatures, think we ought to be doing, we would have irrevocable knowledge that this does, or does not, fit in with the plan.
That, I think, would certainly take a lot of the pleasure out of life; and it's not simply for the joy of the chase, the pleasure we take in pondering these deep questions - rather that when we are free to do as we think best, we know that we are doing things our own way, for our own reasons, for better or worse. The way I see it, making the most of our brief existence, and striving to improve ourselves and our environment, is an essential part of what it means to have a fulfilling life, and I would hate to find out that this is somehow contrary to some pre-determined intention (conversely, I'd also be disappointed to know that that is the plan, again because then we are reduced merely to following instructions, not living for ourselves). Life would basically be reduced to a case of "that's what it's all about then - better get on with it".
The need to be free of any particular plan is all the more apparent when considering some of the alternatives to the absence of a meaning. The Christian tradition, for example, posits that our meaning is for the glory of God, that we are his creations and are here pretty much for his amusement and adoration - I've written about how I'm not too happy with this vision of reality before, but my point here is that if indeed there is such a meaning, it would surely be a horrific thing to know. It would mean that all our efforts are pretty much for nothing, other than as a service to some incomprehensible and ineffable being. The Judeo-Christian tradition is perhaps a rather easy target in this regard, but the same applies to less dictatorial religious viewpoints, which stress personal enlightenment, relvalation and one-ness - such as Buddhism, Zen or Hinduism: if that really is the meaning, then our efforts must presumably be focused on it, and any other endeavours (such as art, science, exploration, love) are ultimately a waste of time.
This brings me to my central objection to any externally imposed meaning of life: that without it, we have done rather a lot of awesome stuff. The past few thousand years have seen us advance astronomically (literally) from our humble hunter-gatherer origins, being capable of sublime works of art and continually going beyond our current capabilities, reaching for the stars, and gaining a greater understanding of ourselves. Certainly, some of this has been tied into mistaken ideas of what it's all about (religious architecture and music can't be ignored), or directly as a desire to find out (after all, "why?" is the primary scientific question) - but I'm sure that a lot of our achievements come directly from this sense of freedom, this ability to choose our goals for ourselves, that comes of not having any set direction.
My point is that we need not burden ourselves with searching for a meaning of life, nor should we be compelled to assign "bettering ourselves", "pursuit of knowledge", "helping our fellow human" or other noble goals as our 'purpose' in lieu of a definitive answer - there simply is no meaning. We must embrace this, since instead we get to decide our own fate, to do what we think is right purely because it is us that it affects: to be the architects of our own future and be judges of ourselves, as a species, on our own merits for our own sake. I'd say we've done pretty well at that so far.