That’s it, really. The new forum description just sent me over the edge.
More specifically, because you run rather than riding a horse. It’s a distinction from polo, the other popular academic sport at the time sports called “football” caught on.
Why can’t Europe, Central and South America, Africa, and Western Asia just call it soccer like the rest of the world?
A common misinterpretation. The “Foot” term actually originates due to the sport’s signature cadence of play calling prior to snap of the ball. The play call cadence, which was originally liltingly sung to accompaniment to woodflute played by the coach on the sidelines, itself derives from 17th century Maori chants. How their early civilization communicated this to western coaching staff is presently unknown and a hot topic of research.
No, no. Surely it’s a well known fact that the ball used to be twelve inches long?
11½ inches, actually, which was the original length of a “foot” based on the size of Charlemagne’s left foot, not the 12 inches of his right foot.
Not many people know this but the length of an American football was derived for the average length of a spoke on a Roman chariot wheel.
Only for about 11 minutes of each 3+ hour broadcast. It should really be called MillingAroundBall.
Yes, just like Foothockey (because you run with the stick) and FootTennis (because you run with the racket), FootRacing (because you run with your feet)…
Some believe that “football” gains its name from the Chippewa term “fult-ba-loh”, which means “to beat one another’s heads in”.
My contribution to Stupid Sports Sayings, vol. 357
“If it isn’t round, it isn’t a ball.”
Rightio old chap; now that we’ve got that sorted, what do you say to a bit of horseball after a spot of lunch? 
Oh, yeah? Well what about a baseball then, huh? No, wait, bad example.
I used to play Foot Hockey in elementary school… except it was actually soccer with a tennis ball.