My goodness so much wrong with this post.
1.) "As a runner, the only time you would ever put force into the legs while the knee is bent 90 degrees is when sprinters come out of the blocks."
You fundamentally misunderstand the point of squatting to parallel. You squat to 90 degrees because that is where all the muscle mass of the knee extensors, the hip extensors, and the spinal stabilizers are working at their optimum capacity. The term in lifting is called "effective range of motion." General strength translates to running strength (think - speed/power development, "core" work, and injury prevention). Why would you CHOOSE to neglect training certain muscles in your legs? With that said, there is a time and place for half/quarter squats, which is demonstrated with the videos of the sprinters doing them posted earlier in this thread. There are also so good reasons why some people prefer to do ATG, but nevertheless, the statement quoted above is incredibly short sighted, ignorant of basic lifting principles, or both. It's like saying "why should I do any rep longer than a mile when I'm only training for the mile."
2.) "What I'm saying is that there are better exercises for the legs for runners than squats."
This is highly, highly questionable, and other than because they are easier/more accessible. I don't think it's true. My guess people are so resistant to squatting is because it's SCARY. Nothing wrong with the lifts mentioned, but squatting is better.
3.) "There are lots of other leg exercises, so these aren't the only ones to consider."
True, but squatting is a full-body lift, not just the legs. There is a reason why there is a debate between the back squat and deadlift as to which is considered "The King of Lifts." It activates everything in your lower body - all the leg muscles, glutes, abs, and lower/middle back. In of itself, it is a far superior lift than the other exercises you lifted above.
4.) "In short, the risk (of injury) vs the reward of the squat FOR RUNNERS isn't as good as the risk/benefit of other leg exercises."
If done properly (like all things), there is very little risk in squatting - it is a fundamental movement pattern. Studies continuously show this. The dark truth is you are far more likely to get injured from RUNNING than you are from lifting weights.