The idea isn't really to make the encryption stronger or to widen the key. It's a classical case of trust - if one cipher is compromised, there are others to cover for you. Also, I wanted to learn the different ciphers, and speed wasn't a top priority.
Yeah, that's why everyone writes cipher cascades. There's a reason you don't see them in any mainstream vetted cryptography. The bigger problem is that none of this is authenticated.