If you aren't doing anything extremely strenuous, then no it probably isn't necessary. But I've done a 100m and 200m sprint and me slamming the breaks at the end generally results in either me feeling faint or simply passing out.
I've never really paid attention to why a cool down was necesary, nor did any of my coaches require it. I just did it because after a good run your sweat glands are wide open and it feels uncomfortable to stand still in the humid, Florida sun.
Wasn't there this story of a 40+ european guy winning grueling competitions based on sheer stamina than performance.It was a story on Nytimes, couldn't find it.
I also feel uncomfortable going from 60 to 0 without a gradual cool-down. My cool-down is pretty short, generally 5 minutes and involves me just moving around a little, drinking some water, and doing stretches. Even if its completely unnecessary, I still prefer to, and stretching is always a good thing.
I've never really paid attention to why a cool down was necesary, nor did any of my coaches require it. I just did it because after a good run your sweat glands are wide open and it feels uncomfortable to stand still in the humid, Florida sun.