for:
min,max,sum,var,std,kurt,median,mad,prod,skew
The big reason to do this is a performance hit when you happen to have an object column. and you don't realize it.
See: http://stackoverflow.com/questions/18701569/pandas-dataframe-mean-very-slow-how-can-i-calculate-means-of-columns-faster
_reduce in Frame already supports this (and Series will ignore it), so should be trvial to implement
alternatively could just pass **kwds thru (I think we had an issue about this earlier)
Comment From: jreback
related? : https://github.com/pydata/pandas/issues/4365
Comment From: jbrockmendel
-1. Working in/around DataFrame._reduce and groupby operations that have numeric_only, it is a PITA and hides bugs.
Comment From: jreback
yep we can just deprecate this i think; do we have an issue for that?