A lot of research goes into speed development. Arm action, foot contact points, kinetic energy transfer, spine angle, etc. Let's make speed development simple - the more force you put into the ground, the further and faster you will propel yourself. Yes, all those other items are important, and doing certain drills for them will help, in some cases more than others. But, first and foremost, having a solid strength base from which to create explosive power will yield the biggest dividends.
A lot of folks approach speed development from the perspective of cone drills, agility ladders, and other standard "footwork" drills. I liken those things to driving a car around a race track. The car might be moving as fast as it can, but it's becoming faster. In order to do that, you must make a physical change to the car. That's the same with athletes - without a legitimate physical change (i.e. becoming more powerful), we won't get significantly faster.
To be fair, the analogy of the car isn't completely accurate. Cone drills and running form drills do have their place. If a kid has too short of a stride, then they need to lengthen it. If their arm action is bad, then it needs to be fixed. Sometimes, all that is needed are a few coaching cues. Other times, there is a biomechanical integrity component that is restricting the athlete. Both of those things needs to be addressed. In the case of an athlete who is capable of better form, but just doesn't have it yet, the coach should indeed look at running form, which can be addressed with some cone drills and footwork drills in certain scenarios. But, to do the most good for the most people, create strength and power and you will create more speed, acceleration, and agility. That should be priority one - extensive cone drills are more akin to driving a car around a racetrack - fast, but not faster.
Solid and complete athletic development will always be the greatest component of a proper speed development program.