This is very true, but I'd also suggest making a big tweak to SS if your goal is not to be a powerlifter. Substitute the front squat and trap bar deadlift for the back squat and deadlift in the program.
If you use bad form on the front squat, you drop the bar. If you use bad form on the back squat, the bar drops you.
Similarly, the trap bar deadlift also makes it easier to keep your back straight and avoids awkwardness (and possible errors/injuries) as you get the bar past your knees.
(Both are suggestions given to me by my boxing coach.)
I'm not convinced that change is particularly valuable. It's not at all hard to learn to drop a bar from a back squat safely--if you're lifting in a power rack (this is mine: http://www.roguefitness.com/rogue-r-3-power-rack.php) it's almost trivial, and if you're lifting off a stand, it takes me about five minutes to show someone how to jump forward.
What's far worse is that good form on a front squat is harder, especially for inflexible people (read: most men.) It takes a wider stance, more ankle motion, and better control over your butt and spine to stay stable. You also can move less weight and it's less of a full body exercise.
Trap bar deadlifts are less problematic but I still wouldn't use them. Rippetoe has called them "a leg press with a bar"--sure, it's easier to stay vertical, but you shouldn't be trying to do that. And while yes, it takes some instruction and practice to learn good deadlift form, that's time you should be spending with a coach anyway.
Mind you, front squats and trap bar deads are by no means bad exercises and are way better than what 95% of people waste their time with; if that's what gets you to spend time under heavy weight, good for you. I just wouldn't tell my friends to go that direction.
If you use bad form on the front squat, you drop the bar. If you use bad form on the back squat, the bar drops you.
Similarly, the trap bar deadlift also makes it easier to keep your back straight and avoids awkwardness (and possible errors/injuries) as you get the bar past your knees.
(Both are suggestions given to me by my boxing coach.)