Folks have asked for the ability to create Durations from floating point values too, and I rejected that for the same reason - using floating point values with time is just begging for bugs, and Walter backed me up on that one.
Makes me think about my money library. It does accept floating point values and it has lead to at least one confused user [0]. Hm.
[0] https://github.com/qznc/d-money/issues/3
