Just to throw my own opinion in, with a bit of personal experience. I was never a great runner– high school prs were 16:08 xc, 10:01 3200, 4:40 1600. My xc time was my most competitive time, and I always wanted to break into the 15:00s but was never able to, mostly due to the fact that I was plagued with constant injuries.
Now, running at the club level in college, I muscled my way to an admittedly mediocre 27:21 8k, but was injured again soon after. Part of my tendency for injuries probably comes from my bad habit of piling on too much mileage too soon, but part of it also came from my running form. I watched a video a friend took of me running, and I realized that I was overstriding like crazy and putting a lot of loading on my legs with every stride.
After my second tibial stress fracture in a year this past fall, I started really studying running form. All those things that AlSal is working on with Ritz- foot placement, arm positioning, higher cadence, and the like. I've now been running low mileage since February, doing 1 or 2 workouts each week and 1 or 2 easy runs, and cross training by cycling or swimming on the other days. On a whim, I went to a club track meet with my running club and ran a 1600. This was in early March, after doing only 1 tempo run and 1 interval workout since I began running. I ran a 4:42 mile, which isn't even a PR, but it came out of nowhere since I had done very little in way of workouts and I hadn;t raced since the fall. The only thing I can really attribute this to is my change in form– thinking of the idea running stride as more circular really allowed me to get going "fast" but not feel as if I were fighting the track, which I always felt like I was doing before I started focusing on form.
Now, I don't think that low mileage and focusing on form will ever make anyone a great runner. However, by focusing on form, which will hopefully lead to a lower rate of injury, I'll hopefully be able to slowly build up mileage and start running some more respectable times.
I think one reason people are hesitant to correct form is because that type of thinking is often associated with form gurus, such as those that we see in Pose or Chi methods. I think its bs to believe that just by buying someone's coaching materials you'll run better, but these methods (in my opinion, Pose more so than Chi), have valuable information for us to learn from. Especially with pose, it's not as if Romanov made up a new way to run– he looked at great runners and asked "What do they do that allows them to train at the mileage, intensity, volume that they do? How do they look when they're racing?" Personally, I'd love to look like Bekele when I'm running, since I believe that will help me avoid injury so that I can really train for a long period of time and achieve my goals. I used to be a form skeptic too, but as an avid swimmer and swim coach, I realized that my focus on drills with swimming emphasized a focus on proper technique to maximize efficiency, and that denying myself that focus in running would ultimately be detrimental to my running. Just my own experience.
Go AlSal, Go Ritz, Go USA