4 points
It gave your horse extra health actually, so not purely cosmetic. But I think in a single player game that also has extremely good modding tools, it doesn’t really matter. If you want to pay to win your single player game, you do you.
Horse armour was mostly a landmark for showing companies that consumers were willing to pay for micro stuff like that. The potential return vs effort invested was crazy. Todd himself said that they try doing nice DLC that gives you good value for your money, but it’s hard to justify business-wise when the horse armour is so cheap to make and sells so well.