The jackhammer currently acts as the ‘key card’ of choice in many end game areas, granting a very easy way around most of the later game door/gate/hacking obstacles, and doing so quickly.
It should really take quite a substantial amount of time/batteries/gasoline to burrow your way through concrete walls (say, 15-30 min) and even more for the steels walls of bunkers and bank vaults (e.g. 1-2 hours). It should also generate enough noise to substantially deafen you without ear protection.
Pickaxe would presumably generate a bit less noise (but still a lot) and drain a ton of stamina and take substantially longer to dig, based on STR.