Because you're Jackie Chan and somebody just killed your uncle?
No, really. It depends on your size, reach, any health conditions, and goals. If you're trying to learn self defense and have no problem with the idea of crippling someone outright or killing them, there are a few different ways you could go. Kung Fu and alot of other combat systems are designed so you can fight, rather than kill. There's the underlying difference. If your attacker is trying to kill you, then he's already got an advantage. I've got terrible balance and no leg flexibility, so most eastern martial arts don't work for me. I have, however, found that combat Sambo mixed with Greek pankration techniques gives me the capacity to dislocate or shatter my opponent's joints, rendering him pretty much useless.
Anyway, it depends.