Although I'm not 100% certain that it's a black and white issue, I cannot imagine any admirable suicide which is based on phsychological issues. The whole "content with your accomplishments" thing is BULLSHIT and I cannot believe people here are espousing that kind of crap. No human being will reach the end of their rope mentally; we only fool ourselves into thinking we do. You can always do more. Unless...
I agree with you. No individual ever know everything, and there will never be a shortage of things to experience, to learn, to perceive, etc... I know that I will never stop trying to learn until the day I die (unless I develop alzheimers...fuck that). However, I interpret the Buddhist decision to commit suicide as an (older) man becoming completely aware and accepting of his ignorance. People generally don't understand what's happening around them in nature, and most of the things they "know" are faulty interpretations about the world that they have inherited from their ancestors (see writings by Heraclitus for better explanations on these ideas).
Well, there are several ways in which a person can react to this. Socrates chose to walk around Athens and call people on their bullshit. He realized that 99.9% of all people (including him) don't know what they're talking about, and all he wanted to do was inform them of their inherent ignorance. We all know how that ended.
I suppose another way is the Buddhist suicide route. I personally would never choose it, but it seems like a man would make this decision after learning and thinking all of his life and coming to the conclusion that we can't really know anything. It's a fairly profound realization to come to, realizing the true limits of the human mind and the human condition. I admit that suicide seems like a cop out in this situation, but maybe the man committing suicide is simply ready to take the "next step." Man is ignorant, so maybe he no longer wants or needs his human body after coming to this realization...
On a more personal level I realize that I, along with the rest of humanity, am ignorant. We are all destined to misinterpret the world around us, and our minds are so fragile and underdeveloped that we can't really "know" how or why things happen; there can only be interpretations that are closer to the truth than others. However, that doesn't give us any right to give up and say that trying anything or declaring anything is a futile task. Some interpretations are better than others, and some decisions are better than others. Nothing we do is ever guaranteed to succeed, but sitting back and assuming everything will be okay guarantees failure. We all have a duty to try and prevent the world from turning into complete shit, even though most of our decisions are destined to fail. All we can do is learn to make better, but not perfect, decisions, which will hopefully prevent man from
completely destroying himself. I guess it's a little something to think about.