Horse shit. In cities, you waded through horse shit.
As someone who has done extensive reenactment in period dress, sometimes in towns dedicated to realism that banned cars and relied on horses for travel, you wouldn’t believe how terrible even a dozen carriages and a few dozen private horses can be to your skirts/trousers and shoes. Especially when it rains.
People sometimes make light of women in the past who changed their outer clothes two or three times a day, but if you were in town, your attire would be absolutely foul after a few hours in the same outer skirt. A long cloak helped immensely to keep your skirts or trousers from soaking up horse sewage.
Once cars took over, that stopped being a problem, cloaks weren’t as desirable as they obscured fashion, and coats became shorter and more for protection from the weather than from horse shit.
There was a bit of military influence, but that was more about fashion than functional influence.