Why is the functionality in grdclip not included (or exclusively) in grdmath?

Today I had to do some calculations with grdmath and then set all cell values < 0 to NaN. To do this I had to:

grdmath ........
grdclip -Sb0/NAN .........

Ideally, this should be possible to do with a single call to grdmath.
In my example only -Sb from grdclip was used, but all the options in grdclip could be included in grdmath.