I can somewhat understand not liking high rep snatches and clean and jerks for most athletes. If you are not a proficient olympic lifter your technique will probably turn to crap, and if you are you are probably more concerned with developing strength and power through low rep lifting than with metabolic conditioning. That said, if your goal is a high level of generalized fitness, I think that developing the ability to clean and jerk a moderate load for high reps with good form is certainly a worthwhile goal. If we are going to define fitness as Crossfit does, then it is even a necessary goal. If you start out with a medicine ball or broomstick, and move up over the course of several years to a 135 lb. bar, with a competent coach giving you feedback on technique, I find it hard to believe that this will lead to many injuries.
That said, barbell thrusters and high pulls, and dumbbell or kettlebell long cycle clean and jerks, one arm snatches, and squat cleans for high reps are effective and less technically demanding than barbell clean and jerks and snatches and offer most if not all of the benefits. I have wrestled, run cross country and middle distance track, played rugby, and rucked with a 115 lb. pack for 5 miles, and none of that compared to the fatigue and full body involvement and concentration of high rep Crossfit workouts. For someone who has to be ready for anything, anywhere, I don't understand how a workout program that always separates cardiovascular training from strength training implements can compare to Crossfit workouts. No amount of sprints, rowing, or other forms of metabolic conditioning will have the same overall impact as a Crossfit-type workout.
As for the common assertion that Crossfit doesn't develop its own, I have seen it do just that in myself and others. My friend Brendan Gilliam at CFHQ came to Crossfit skinny and without a single muscleup and can now overhead squat 225, do muscleups with a 50 lb. vest, and run 25 miles with no long distance prep. I fell over with the bar the first time I tried an overhead squat four years ago at an exceptionally muscular 140 lbs. bwt. and now I OHS 165 lbs. for five sets of three at 172 bwt with a 220 lb. power clean. I am running faster track workouts now than when I was 15 lbs. lighter and running 5 days a week for high school track with a 5:12 mile. I would never have even come this far without Crossfit, though I am very far from satisfied with my current level of fitness.
The underlying question in the debate is how well Crossfit workouts like Grace and Fran carry over to other domains. If you think that their effects merely test one's ability to do Crossfit and say very little about anything else, or that other workouts can effectively simulate their effects with less risk, then it doesn't make much sense to do them. If you think that the fitness that Crossfit workouts develop is unparalleled and transferrable to most real world activities, then it makes sense to accept a certain amount of risk, and to aim to minimize that risk through competent coaching. I think that determining the answer to this question conclusively would be impossible. Therefore it is up to each of us to find out what works in our particular circumstance. In my case, and in the case of most of those whom I've trained with, high rep lifting and Crossfit-type workouts are irreplaceable. It is not just a question of preference, but of performance.