Most of us can agree that sometimes people have to die. Most of us have the capacity to understand that the US isn't evil when it accidentally kills Afghani civilians, and some of us can accept that Israel can't protect itself without causing some civilian casualties due to the intermingling of the militants and civilians. In general, we understand that sometimes people die when you're trying to get something accomplished. It's apparent that the Palestinians have some grievances against Israel, and their terrorist actions are legitimate means of fighting against oppression. The problem is that there exists a mental disconnect between a realistic end to oppression and the goals of terrorists. The suicide bombers don't die knowing how their death will advance the Palestinian cause, although it's likely that their heads are souped up to think it will help somehow.
The reality is that the Palestinians will only be well off when the Israelis feel comfortable giving them what they need. That's not a far fetched scenario given how strong the Israeli left is, if only there was some time of peace. But Labor isn't going to win the PM seat when all the terrorism is happening. Of course the details of Israeli politics may be lost on the low-level suicider, but the political leadership knows exactly the results of the terror.
So while the Palestinians have real problems, their terror isn't aimed to solve the said problems. In that light, it's obvious why this terror should be condemned by organizations like Amnesty International: it kills innocent Israelis, it makes malleable Palestinians kill themselves, and it sets back the Palestinian cause.
Why No One Will Fight ANymore
Back in the day when men were men, it was only natural to go to war. Being born with a penis entailed the duty to fight (and possibly die) for your clan, tribe, country. By the same token, being born with a vagina entailed the duty to cook, clean, and birth children as often as possible.
In the last hundred years, or even longer, the notion that women "have to" do anything just because of her gender has been stomped into the ground. We are destroying gender roles all the time. These efforts are aimed at women, of course, but they have an unintended side-effect. Namely, if you aren't obligated to domestic duties by your gender, why should my gender obligate me to fight (and possibly die) for you? We did away with gender roles, so now a man doesn't feel like its his job to unquestionably go and fight. And who, in their right mind, would volunteer themselves otherwise?