Metric Soaring

Clearly metric is a superior system for most expressions
of measurement, but it seems surprisingly inefficient
for flying (especially soaring) in it's current form,
which brings me to my question(s).
Why do metric variometers read in m/s, instead of kph
when the metric airspeed is in kph? Would it not make
more sense to use kph on the vario too so quick mental
L/D calculations could be done (for those who do not
use a flight computer etc to think for them)?
After doing a little homework, I figured out a 5 m/s
is 18kph (1m/s is 3.6 kph). If I used metric to fly
(I'm just plane knots) I would much rather have a vario
that went up/down to 20kph, and was hash marked on
single kilometers with numbers every 5th hash mark
for the main vario.
For a weak lift unit it would be hash marked for 1/5
kilometers but numbered every whole kilometer up/down
to 5kph.
Strong lift versions would be up/down to 30 or 40kph,
hashed every second kilometer and numbered every 5th
hash mark...Just a thought, but makes me curious.

Paul Hanson
"Do the usual, unusually well"--Len Niemi