So one of the ways of calculating Isp is:
Isp = Ve/g0
You divide the effective exhaust velocity by acceleration at earth's surface. This gives you a number in seconds, and is generally considered helpful in determining an engine's efficiency.
My question is why the g0 variable? Since Isp in seconds is used for all manner of spacecraft, many of which spend years in space (probes with ion thrusters), what's the point in that g0 variable.
Would it not be more informative to simply list the effective exhaust velocity?