To be clear, I'm not suggesting that we actively support `dicttoolz` to be used with any object that support the mapping protocol.  I'm just open to the idea that some users at some point (myself included) may use non-dict mappings, and `methodcaller` makes this easier.  If one of us at some point wants to use `dicttoolz` with non-dicts, *then* we can actively develop support for this into `toolz`.

If you think otherwise and would like to use `dict.values` because it's more clear, I can be convinced to change it.