Slip joint knives are classic and have been around for centuries since they have been invented in the 1600s in England.
They are traditional and classy and can be dressed up or dressed down.
They are not as dangerous as one may think; the false sense of security that brings a liner-lock is comforting until your finger inadvertently catches the lock… Remember that boy scouts have been faithful to slip joints for generations.
There are places where flashing a one-hand opener with a locking blade may be frowned upon, and an elegant slip joint, slowly opened with two hands, will not draw the same attention, while getting the same job done, and there are cities and even countries that will not let you walk around with a locking knife.