Fuzziness in Life

People tell me that science and developments in medicine will help us prolong our lives and take us closer to immortality. I don't believe that. I believe that death is inevitable; and that death is necessary to keep the human race going. Keeping the same batch of humans alive for centuries together will stagnate thoughts and ideas (not to mention evolution). However, I do think that developments in medicine will allow us to take away the fuzziness in life. Human beings, today, die (and grow) gradually: at least most of us do. We are born small, weak and incapable of doing anything. Then we slowly grow to our full height and strength. We grow to our full mental capabilities. We are at our peak at the age of 22-25. Then the decline starts. Sure, there are exceptions, but the percentage of such exceptions is low. Most people start losing bone density, physical flexibility and strength, mental sharpness as they go through their thirties, forties, fifties etc. By the time most people reach 80 (assuming they live that long) they are too weak and incapable to do anything meaningful (like I said earlier, there certainly are exceptions, but the percentage of such exceptions is too low to make a difference). I feel that this gradual development and de-generation of human beings takes a heavy toll. It is a huge waste of time. If you do not take advantage of your twenties for some reason, your chance is gone. Also, aging takes such a huge toll on the psyche of individuals: most people lose their self-confidence and start considering themselves a poor image of what they were 10, 20, 30 years ago. I think we should focus our medical developments on removing this waste of time. People should be able to take birth in a fully developed state, live for 20, 30 years in that state, and then die suddenly while still at the peak of their abilities. There would be no waste in development or de-generation time. Of course, people will miss their childhoods, but if you had to choose between 10 years of childhood and 30 years at the age-equivalent of 22, would you not rather choose the latter option ? What does the child in you say ?