Rot's primary goal is crypto agility: you should be able to easily change secret values as well as the ciphers used to encrypt your stuff. Rot provides a robust rekey mechanism to ensure you're using the best encryption available.

So the naming of rot is because cryptographic keys have a tendency to "rot" rather quickly. Frequent use of keys inevitably leads to leakage and/or compromise, and the underlying encryption algorithms may not be secure in the future. Cryptographic material doesn't age well in general.