Hi, yesterday I asked in the Simple Question & Simple Answer thread why this site is called Smogon University and not Koffing University, but no one could really answer it. The credits list you as the one who came up with the name. So why?
But the difference between the tomato example and an embryo is that the embryo will eventually become human. To not account for the potential value is the same as throwing away bonds before you can cash them because, "they're not worth anything."
As for what we have to gain by considering them human at fertilization: by doing this we are protecting the rights of what will eventually be a person. Future people have rights too. Otherwise there'd be no reason for us to use natural resources responsibly or avoid causing massive pollution.
What I was asking is this: Since we don't know when an embryo becomes valuable why not decide that it is human at fertilization? What do we stand to lose? The way I see it is that there is a myriad of problems caused by an unwanted pregnancy. But they all have more elegant solutions than abortion. Better sex education to prevent people who don't understand contraceptives from having sex. Better teaching people to accept responsibility for their actions so they don't feel entitled to end a life to better suit their own. Better raising of men to make them be men and accept responsibility for getting a woman pregnant. Better adoption system. Etc.