If you're a bodybuilder, machines are tools as a means to an end. If building muscle is your goal, nothing wrong with the squat machine or the Smith. There are amateur and pro bodybuilders, natural and juicers who have never done free weight barbell squats but have legs which can rival and surpass any powerlifter, period. Evidence; Wong Hong, Dorian Yates, my friend Ernie (Mr Junior Malaysia) who's a natural, these guys don't do free weight barbell squats. Why waste time developing functional core? It's a waste of time, IF you're looking to gain pure muscle mass. My 0.02, don't ever get drawn into the hardcore mentality of free weights or go home. You'll be severely hampering your progress in muscle development.

However, if just purely strength is your goal, the free weight squats is your only option.