Historically, the staff was the weapon of choice for the rural walker when the powers-that-be wouldn't let you have weapons - at least in Europe, where there's a lot of wood - 'cause you could say it was your walking stick. It wasn't too much of a threat to an armored man, and it could be used to fend off or beat back hostile animals or robbers (who, often being as poor as you, didn't tend to have the same quality arms and armor of the powers-that-be), whereas if you had a bow, they'd think you were a poacher, and if you had a melee weapon, you'd best be of the right class or you're in trouble. If they took it away, no great loss - just go find another. (Assuming of course the local ecology has some sort of stick of sufficient length and strength to be pressed into service.) Also very useful for walking.
Pretty much the same might apply in Traveller - go to some high law world and it might be as good as it gets for your foray into the hinterlands.
And, if some mischance left you stranded in the hinterlands without adequate power or ammunition, then a staff or an improvised spear might be your best bet for survival. And a sling - also a very useful thing to learn if you're the wilderness-foray type.
If you're going to spend your every minute in the ship tweaking the engines or in urban alleys negotiating with thugs, you're probably never going to need a staff - and you might draw unwanted attention with one in some places. If on the other hand you go adventuring into the wilds, you just might find yourself in a situation where one might be useful.