If I were to ask a sample of people whether they felt that life, in being full of the things they relished and loved, was ultimately worth living, even after prematurely contracting a double case of bone and stomach cancer while having no access to medical care or pain relief, I imagine that at least some of them would feel that it was; overall, they'd contend that their objects of adoration and enjoyment were worth the horrific pain.
Now, if I were to present that same sample of people with the same circumstances, but in the form of a deliberate offer, I imagine that the results would be quite different. Suppose that, instead of asking whether life is worth living in spite of contracting horrible diseases, I said, "I can give you everything -- everything -- that you've ever wanted in life, no matter how lofty or unusual. Love? Riches? Intense physical pleasure of various sorts? Simple contentment? Beauty? It doesn't matter. I can give you all of it. The problem, though, is that, in order for you to take these things, I'm going to have to make you pay by giving you both bone and stomach cancer, and I'm going to make them incredibly painful. Furthermore, I'm going to make it so that no medication can work to fight this incredible pain as you slowly die over a period of two years. Sorry, but that's the kind of energy sacrifice that I'm going to have to make in order to keep your life balanced. Still interested in the riches and the love and all the joys and wonders?"
I don't know if anyone would seriously consider the offer.
What is it about the former case that seems, at least to me, so dramatically different from the latter? If I were to guess, I'd say that it's the addition of mystery. Because the horrific pain and suffering are not being directly administered by a fellow human, there's something unknown and "beyond us" about it. Therefore, it's acceptable.
This, quite plainly, is a by-product of our evolution; when we acquired the capacity to reason by way of manipulating linguistic objects, we were not omniscient. Thus, if we were going to remain evolutionarily successful -- and, consequently, wrapped up in the meaningless agenda of life on Earth -- we were going to need to be in awe of that which we did not understand or control. Once you recognize that it's all manipulative psychology designed to promote your own survivability -- and the survivability of your offspring -- you realize pretty quickly that none of the above mentioned desirables are really worth their prices. Perpetuating them into the future by creating copies of ourselves, therefore, is incredibly idiotic, and quite criminal.